Click on images to enlarge or to see full sized drawing.

One subject that comes up frequently is how to identify barrels on various models of ground type M1919 BMG's. All of the numbers, letters and symbols imprinted on the barrels have meaning. We hope to shed some light on this subject by offering the following observations.

This particular article limits it's scope to ground types, that is only those M1919s that were used in ground operations which would include infantry, cavalry, armored units, etc.

All air cooled members of the .30 caliber Browning Machine Gun family have a common ancestor 1n the M1917 water cooled "Heavy". The M1917 design was modified late in WWI into a 18 inch barreled air cooled weapon for use in tanks and was actually called the Model of 1919 Tank Machine Gun. WWI ended before very many of these weapons were produced. The manufacturer of the air cooled tank gun, New England Westinghouse, saw their contract shrink from 40,000 to 10,000 to 500 actually produced.

WWI doctrine used machine guns, primarily, for defensive applications as they tended to be water cooled, very heavy and were mounted on equally heavy wheeled or stationary tripod type mounts. The weight of the mount and the weapon produced an extremely stable firing platform, and many times machine guns were viewed in almost the same context as artillery, right down to developing methods of indirect fire and machine guns in U.S. service being organized into separate battalion level units in divisional organization.

There were some attempts to produce lighter air cooled automatic weapons for use in the attack, the Lewis Gun, with it's signature circular horizontally mounted magazine and stove pipe barrel jacket and the M1918 Browning Automatic Rifle, both were successful designs. They were light enough to be carried by one man, and had the ammunition supply attached to the weapon. However, even though the Lewis had a magazine capacity of 47 rounds, over twice the capacity of the BAR frequent changing of magazines reduced their effectiveness. There were also less than successful attempts to produce an automatic weapon for the attack, most notable was the infamous French C.S.R.G. (Chacuchat) The politest thing one could say about this poorly designed and equally poorly manufactured weapon was "not combat reliable". The U.S., being desperate for automatic weapons purchased about 19,000 in caliber .30'06 and used virtually none. Reportedly, U.S. troops refused to carry them into combat.

What was really needed was a rifle caliber weapon more portable than the water cooled "heavies", yet still capable of some level of sustained fire, that could be more easily advanced with the attacking infantry. In short we, and everybody else, needed a rifle company, rifle caliber automatic weapon.

Following the Armistice, on November 11, 1918 the United States rapidly reverted to it's isolationist comfort blanket. The military forces shrank nearly to pre WWI levels, budgets were slashed and weapons development nearly disappeared.

If any one branch of the Army is to be credited with development of the 1919 air cooled ground type BMG into a viable weapons system, it's the Cavalry. The Cavalry, still horse mounted, was attempting to remain relevant in a rapidly mechanizing environment, and realized that some sort of readily portable automatic weapon was necessary to increase the combat power of mounted troops. Their first choice was a modified BAR, the M1922, apparently this wasn't exactly what they had in mind so they switched gears and in 1930 acquired a M1919 tank machine gun and added sights, developed a tripod mounted to the weapon by the pintle hole rather than a barrel jacket clamp like the original tank dismounted tripod, and presented it to Ordnance as a prototype of what they wanted. Subsequently, the RIA ordnance committee recommended that the "Machine Rifle Cal. .30 M1922" be declared obsolete on April 10, 1941. Sometimes it takes a while, in this case 11 years, for even things that aren't required to work their way out of the system.

In 1931 the Infantry followed suit and began to experiment with an air-cooled weapon. Both the cavalry weapon which became the M1919A2, and the experimental infantry weapon which became the M1919A3 were equipped with the 18 inch barrel and slotted barrel jacket from the tank gun. When the tank gun was developed in 1918 Ordnance was using the Class and Division system of numbering drawings and the 18 inch barrel was shown on drawing 51-18-5C.

Click on image to see full drawing.
The M1919A2's barrel's assigned "piecemark" was 5A1 on this drawing. Other parts of the barrel assembly, the "muzzle attachment" (front barrel bearing) and the "muzzle attachment plug" (booster plug) , along with the barrel jacket and barrel jacket ring were shown in other details on sheet 51-18-5 . This drawing detail was renumbered on June 1, 1931 to D8793.

Click on image to see full drawing.

This is detail D of drawing 51-18-5 showing the M1918 tank gun barrel jacket with the elongated cooling slots that remained with ground type air cooled BMG's until 1939. On June 1, 1931 all of the original 51-18 Tank Gun drawings were redrawn and converted to the letter prefix system which had only one part to each sheet. This drawing became C9819.

Ordnance seemed to use the term "tracing" interchangeably with the term "drawing". Actually, "tracings" were made on velum which is a translucent hard finish medium similar to parchment paper. The tracings were used to produce copies of the drawings by the "Blueprint" process where a specially treated paper was moistened, covered with a clear glass plate, which was then covered by the velum tracing and another glass plate and exposed to light. Light, acting on the chemically treated paper through the vellum tracing, produced a sort of negative image where the dark lines on the tracing became white lines on a dark blue background, hence the name "blueprint". For some time this was the only method available to make copies and, it remained in use into the early 1960's. Occasionally, even today, you will encounter a "blueprint" style drawing copy especially in land survey documents dating in the 1960's

Today the term "blueprint" has a totally different meaning. In automotive parlance "blueprinting" describes an engine that has been carefully assembled with specially selected components. In common use, "blueprint" or "prints" means any sort of drawing used to construct, or fabricate anything from a birdhouse to a nuclear submarine.

Later in the article you will see an actual "blueprint" copy of a barrel jacket drawing.

In the Class and Division naming convention automatic weapons were identified as Class 51. The M1917 was a Division 10 and the M1919 tank gun was Division 18. When the Class number was combined with the Division number, it produced a Major Item Number. In this way the M1917's Major Item number was 51-10 and the M1919 tank gun was Major Item 51-18.

Very few parts produced during and immediately after WWI were required to have the piece mark imprinted on the part, however they were usually marked with the manufacturers symbol, and certain parts namely barrels, bolts and barrel extensions were required to be proof fired with special high pressure test cartridges. These parts were marked with a proof mark, an upper case "P", and the world famous Ordnance "Flaming Bomb" property/acceptance mark. The original 18 inch barrels for the tank guns were produced by New England Westinghouse and they were most likely marked with a W in a circle. This policy of not marking the all of the parts with the piece mark continued well into WWII production. Some of the parts, even large parts like the barrel jacket, were never required to be piecemarked, however some jackets may have been. The marking, or lack thereof depended on the whether or not the drawing required the part to be marked, and in what location and, apparently, the whims of the manufacturer. Saginaw Steering Gear Division of General Motors, the all time M1919A4/A6 production, quality and price champion must have issued a "flaming bomb" stamp to nearly every one in the factory and encouraged their use. Saginaw built weapons have "flaming bombs' everywhere. Drawing B169913, which was not a drawing of a part at all, contained tables showing which M1919A4 parts were required to be imprinted and the authorized manufacturers codes.

The barrel markings were not always applied in the locations specified on the drawings.

1936 seems to be the air cooled Cal. .30 BMG's watershed year, the Rock Island Arsenal completed production drawings for the M1919 family, both the Infantry, and the Cavalry who were busy trading in their steeds for scout cars, had concluded that a 24 inch barrel was better suited to their needs, and the decision was finalized to convert some excess M1917 water cooled BMG's left over from WWI, the few M1919A2 Cavalry models, M1919 tank guns and any other experimental weapons lying around to the new air cooled M1919A4 weapon.

The Rock Island Arsenal publication titled "NOTES ON THE BROWNING MACHINE GUN CAL. .30 M1919A4" dated March 18, 1937 set forth everything that you needed to know about the weapon conversion program right down to Section VIII Paragraph 2 which instructs which type of lubricant (class A or Navy contract oil 2110) and cautions that the "Bolt, barrel guide, extension and other moving parts should be cleaned if practicable and be lubricated after firing not more than 10,000 rounds". 10,000 rounds seems like a lot, especially with corrosive primers, that's 40 M1 Ammo boxes with 1-250 round belt per box.

Figure 2 of the 1937 "NOTES" document has a great right rear quarter photo of a early non-production prototype M1919A4 rebuilt from a New England Westinghouse M1917. This atypical M1919A4 complete with M1917 style trigger latch (safety) back plate, slotted barrel jacket, new flanged bottom plate with integral T&E attachment and a finger flanged offset bolt latch required because of some sort of reinforcing applied to the rear of the side plates. This additional side plate reinforcement was likely replaced by the later heat treatment of the rear most inch or so of the production side plates. This photo also shows new sights, and the spring clip on the bottom of the pistol grip. Note that the bottom plate flange rivets are ground flat and are not the later dome head style. This document is the first mention of the assignment of a Major Item identifier of 51-83 for the Fixed and 51-84 for the Flexible M1919 weapons.

The "NOTES" document also stated that it was to be considered to be the "instructions to the using services until a S.N.L. could be prepared."

March 29, 1938 brought an addendum to the original "NOTES" this one was titled "NOTES ON THE BROWNING MACHINE GUN CAL. .30 M1919A4 MODIFIED" which dealt with a few refinements in the design of the belt feed lever, a .047 wire driving spring combined with a .617 inch hole in the booster plug changing the rate of fire to 500 to 600 RPM, dome headed style rivets to secure the rear of the top plate, and modifications to the hold open feature of the top cover.

Right: FIGURE 1 from the "Modified" notes looks more like what we are used to seeing except for the slotted barrel jacket. This photo still shows the M1917 style trigger safety bar back plate. Note the dome head rivets securing the bottom plate to the side plate. The driving spring and the .617 booster plug were not adopted.

RIA Ordnance Technical Committee meeting #46 on November 10, 1938 discussed Item 14772 which outlined tests of, and made a final for the record recommendations for the substitution of barrel jackets with round holes for the slotted type. The Committee concluded that the jackets with round holes cooled just as well, were easier to fabricate, were stronger, and had a satisfactory record on M2 Aircraft BMG's.

The 1919 BMG ground family includes the M1919A4, Fixed and Flexible, the M1919A5 Fixed, the M1919A6 Flexible, M1919A4E and postwar the M37. All of these weapons with the exception of the M1919A6 used the same barrel designs.

The WWII era producers of what was to be officially known in the 1940 dated Field Manual FM 23-45 as the "Browning Machine Gun, Caliber .30, H.B., M1919A4, Ground" were:

RIA, Rock Island Arsenal, Rock Island, IL

SG, The Saginaw Steering Gear Division of General Motors Corporation, Saginaw, MI Some parts, but not barrels, likely produced at Saginaw's Grand Rapids, MI plant are marked S.G.

BA, (BAC has been reported) Buffalo Arms Corporation, Buffalo, NY Buffalo Arms was a subsidiary of the Houdaille-Hershey Corporation formed solely for the production of armaments during WWII.

BCI (BC has been reported) Border Cities Industries, Windsor, ON, Canada. Border Cities was a GM, Canada subsidiary which manufactured M1919A4's for British Commonwealth countries, chiefly Canada.

All of the manufactures of the Caliber .30 air cooled ground family of BMG's also produced barrels marked with their identifying code.

Machine gun barrels, especially in air cooled weapons, wear out rapidly. Heat and friction are the enemy of any mechanical device, and machine guns are no exception. Each four man M1919A4 team carried an extra barrel and a set of asbestos barrel changing gloves with each weapon. Each manufacturer supplied great numbers of replacement barrels. SNL A-6 dated May 28, 1941 called for 400 spare barrels per 100 weapons for one year in a theatre of operations.

In addition to the prime contractors, several other companies supplied barrels:

GL, The Guide Lamp Division of General Motors Corporation, Anderson, IN

It has been reported that General Motors Corporation, Detroit, MI under their corporate name, and The Crane Company, a Chicago, IL manufacturer of plumbing fixtures, also produced caliber .30 air cooled barrels. It is not now known what manufactures code were used to mark the supposed GM and Crane barrels. It is well known, however, that the Crane Company was an early experimenter and producer of "Stellite" bore liners for Caliber .50 BMG barrels.

By 1936 when the M1919A4 design was more or less finalized, Ordnance had mostly converted the numbering of the actual drawings used to fabricate parts from the old Class and Division system to the letter prefix system. In 1922 Ordnance, using the experience gained from WWI, implemented mandatory physical sizes of the medium the drawings were prepared on. They are: (in inches) Size A=8 1/2X14 Size B=12X20 Size C=18X30 Size D=24X40 Size E= 40X necessary length

Since the M1919A4 was a "new" weapon at least from the trunnion forward, the barrel drawings started with letter prefix drawing number D35233 dated September 30, 1936. The drawing shown below went through 14 Revisions the last, Revision 14, was dated 4-7-42.

Click on image to see full drawing.

Both Class and Division and letter prefix drawings showed a "piecemark", which after 1943 was supposed to be called a "part number", but in practice was not. The piecemark is the identification for the part (s) shown on the drawing. While each part had a piecemark, not every part was required to be marked. The drawing for the part, even in the old Class and Division system of numbering drawings, indicated how, where, and in what size the part was to be marked.

The drawing above requires the piece mark of D35233-14 to imprinted longitudinally on the barrel about midway between the muzzle and the chamber in 1/16 inch characters. It also requires that the "P" indicating that the barrel had been proof fired, be imprinted in 1/8 inch characters about 4 inches and 90 degrees clockwise, as viewed from the chamber end. From the drawings observed this is the standard location prescribed for marking barrels. As we will see later, the barrels were usually not marked in the locations specified on the drawings.

Besides the piece mark, and the firing proof mark the barrels were supposed to be marked with the manufacturers identification, the ordnance flaming bomb, and were usually marked with several other letters or symbols most likely to identify which production line and company inspector produced and inspected the barrel. This marking would come in handy to track down the source of barrels that were rejected by government inspectors.

The location of the flaming bomb and the production markings varied, but the manufacturer's identification was usually near or directly following the piece mark.

There is some confusion regarding the appearance of the piecemark on M1919A4 barrels and other parts. The required piece mark is D35233, however the mark D 35233 and D-35233 all with various Revision suffixes have been observed.

From my examination of available Ordnance records there is no significance attribution to spaces, dashes, or lack thereof. These differences are, in my opinion, some random event that varies even with the same manufacturer. It is likely that these differences are the result of confusion in the tool room where the die stamps were made.

The piece mark suffix numbers observed on M1919A4 barrels are D35233-6, D35233-12 and D35233-14 these suffix numbers represent Revision numbers on the D35233 drawing.

Above is a photo of a Saginaw Revision 6 barrel. The firing proof "P" is located directly below the "G" in SG , the ever present flaming bomb is just visible below the "23" in the drawing number. The two C's are likely factory markings used to identify the production source of the this barrel which is shown in it's original finish. Note the space after "D". Revision 6 dated 10-3-40 apparently had to do with changing the quality of the finish of the barrel between the bearing surfaces, and subsequently changed the piece mark to D35233-6.

The original, that is the unrevised, barrel drawing contained a detail drawing of both the chamber and the barrel rifling Revision 12 dated 11-28-41, with piece mark D35233-12 removed this detail by crosshatching and added "NOTE: FOR CHAMBER AND RIFLING SEE DWG. C64321." This was probably done to remove the possibility of different drawings with slightly different dimensions being used to cut chambers and rifling in different weapons. The C64321 drawing became a single "go to" reference drawing for everybody cutting chambers and rifling barrels at least for BMG's. This would add another level of uniformity to the very critical business of chambering and rifling weapons all using the same ammunition designed to function in all weapons.

The above photo shows a refinished Saginaw Revision 14 barrel. Note the dash between the D and the drawing numerals. The firing proof is located below and to the left of the D, the flaming bomb is can be seen about inch below the SG and the lower case "c" factory mark about 1 inch to the right of the SG. All markings are 4 inches from the chamber. Some barrels are marked on the long axis of the barrel, like this example, while others are roll marked on the circumference of the barrel.

Above are two Buffalo Arms D35233-14 barrels. Note the dashes between every part of the imprinted piece mark. There is no apparent rhyme or reason for the dashes as they follow no pattern and have no known meaning. Many Buffalo Arms barrels have the circular tool marks that are prominent in this photo.
                                                      Photo courtesy of "rdulina" forum.

The final observed piece mark D35233-14 was a result of Revision 14 dated 4-7-42 this revision does not appear to have accomplished much of anything except change the piece mark.

From September 30, 1936 to 4-7-42 very few dimensional changes besides a few minor tolerances changes were made to the barrel, other than the chamber detail which was removed by Revision 12. In any event, the barrels, regardless of suffix markings, manufacturer's identification marks or miscellaneous inspection and production stamps are fully interchangeable among the various 1919's except for the M1919A6 which used a different barrel design in an attempt to save weight.

If you have a barrel marked D35233 it was made after September 30, 1936 and before 10-3-40.

D35233-6 marked barrels were produced after 10-3-40 and before 11-28-41.

D35233-12 marked barrels were produced between 11-28-41 and 4-1-42.

The D35233-14 piece mark indicates a production date between 4-7-42 and 5-10-48 when the drawing D35233 by Revision 22 was converted to the 7 digit naming convention and became a D size drawing numbered 6535233 and changed the part number (piecemark) to 6535233.

A note of clarification is in order. The production date spans quoted above are not absolute they only state times in the past tense. That is, a D35233-6 barrel could not have been produced BEFORE 10-3-40 because there was no drawing authorized to mark it as such. However, just because the Revision 6 appeared on 10-3-40 doesn't mean that D35233 barrel production halted and the next day resumed with D35233-6 barrels. There was some unknown time lag between preparation and approval of the drawing, dissemination of the drawing and actually implementing changes to the part and to the associated piece mark

If a producer of barrels didn't get the new drawings they just kept producing barrels from whatever drawings that they had on hand unless someone told them not to. Even if the manufacturer received the drawing in a timely fashion, it took some interval to get the work force on board or even make up a new die stamp.

There is likely considerable overlap in the production dates of piece marked barrels with or without revision suffixes.

While all of the manufacturers of the M1919A4 produced barrels only Saginaw and RIA produced A6 barrels during WWII with Saginaw being the only WWII producer of purpose built complete A6 weapons. The drawing D54559 dated July 27, 1943 is the first incarnation of the A6 barrel.

When one looks at the subject of barrels for the 1919 family, the question of barrel jackets invariably comes up. The air cooled BMG's require a jacket to support the front barrel bearing surface that supports the weight of the much heavier barrel required by the absence of a water cooling system. The M1917 water jacket assembly contained an integral support for the front of the much lighter M1917 barrel. The original A2 and A4 slotted barrel jackets had the barrel locking screw hole and it's associated trunnion threaded screw hole located on the top of the barrel jacket and trunnion While this location was just fine on the A2 with it's front sight located on a band on the barrel jacket near the muzzle, it was blocked by the front sight located on the front of the trunnion in the production A4's. With the adoption of the round hole barrel jacket these holes were relocated to the right side of the trunnion block and jacket. Eventually, barrel jacket to trunnion assembly required that the jacket be sweated to the trunnion threads with "Minimum 500 degree F" solder in addition to the locking screw being staked in place. Barrel jackets were never officially required to be imprinted with piece mark/part numbers.

Drawing C45950 dated January. 18, 1936 is the earliest dated drawing we have discovered that depicts a barrel jacket with round cooling holes. The next drawing of the jacket is C62503 showing slotted jacket with a date of January 20,1936.
Click on image to see full drawing.

Click on image to see full drawing.

This undated drawing, or rather blueprint copy of drawing C9819 is the earliest indication of a barrel jacket for the M1919A2E3, the experimental 24 inch barrel version of what would ultimately become the M1919A4. It appears that a blueprint copy of drawing C9819 the 18 inch barrel tank gun jacket was made and hand notes indicate the new length, 19.08 (-.002) and the new drawing number C45950. The two vertical wavy lines intersect the jacket between slots indicating a break in the part drawing. The note to the left says "add additional slots for additional length". In the upper right hand corner of the C9819 drawing blueprint copy, the number and date were lined out and the hand written notation "New Part" was entered. In the "Drawing Pertains To" block, the notation M1919 tank gun was lined out. Copying a drawing, and making hand notations to indicate changes to be made is a common drafting practice.

Now is where things get really murky. Even though the above drawing indicates that the 24 inch barrel version of the slotted jacket was to be shown on drawing C45950, the earliest version of that drawing dated 1-18-36, shows round holes instead. However the unrevised, version of Drawing C62503, dated 1-20-36 shows slots until Revision 2 dated 9-6-39 when the slots became holes. Both the original C62503 drawing showing slots and the C45950 that was supposed to show slots but had holes were superseded, by the C62503 Revision 2 drawing. Notations on C45950 also indicate that it was superseded by C62503 on 9-6-39. We are unable to explain the discrepancy in the dates. If C45950 was earlier, why didn't it show slots? Conversely, if C62503 was later why did it have the slots? Being later it should have had round holes one would think.

Drawing C62503 originally dated January 20, 1936 showing the early slotted jacket. The legend at the bottom notes: "SUPERSEDED BY NEW TRACING C62503 UNDER REVISION DATE OF Sept. 6, 1939" With a wave of the Ordnance wand, the slots disappeared, and the holes appeared and the drawing number remained the same. Houdini couldn't do this good.
                                                             Click on image to see full drawing.

The best explanation for all of this is, that after the RIA ordnance committee recommended the change from slots to holes on November 10, 1938 it was decided to substitute the C45950 round hole jacket drawing for the C62503 slotted jacket to avoid having to have to change all of the documentation that had already been produced. This would work because the DRAWING NUMBERS would remain the same, but the actual part depicted would change. SNL A-6 dated May 1941 still shows a slotted jacket on the A4 with the drawing number C62503 and SNL A-6 dared September 1943 shows the round hole jacket WITH THE SAME C62503 DRAWING NUMBER as the 1941 version of the SNL. We do not know why it took from the Ordnance Committee meeting on November 10, 1938 until September 8, 1939 switch the drawings around.

C62503 REV 8, dated 1-18-43 It is difficult to see but This starts with REV 2 dated 9-8-39 There is no REV 1. REV 2 swapped the C45950 jacket with holes for the C62503 jacket with slots. The respective parts remained the same, but the drawing numbers were changed or superseded.
                                                                  Click on image to see full drawing.

This is a copy of drawing (C)5562503 REV 9 the M1919A4 barrel jacket. REV 9, dated 5-10-48 changed the drawing number from C62503 to the "new" 7 digit format and also changed the part number (piecemark). This is the last version of the drawing of the M1919A4 barrel jacket that we have been able to obtain.
                                                                Click on image to see full drawing.

Drawing C93962 dated July 22, 1943 is the earliest version of the M1919A6 jacket it's overall length is 16.584 inches.
This jacket was designed for use with the one piece booster/bearing and the snap ring retainer for the bipod head.

Click on image to see full drawing.

Click on image to see full drawing.
Drawing (C)7160455 with no revisions is the last and shortest (15.954 inches) of the A6 barrel jackets. This version replaced the earlier and longer A6 jacket depicted on drawing C93962 above. The original drawing date is March 21, 1944. The 7 digit drawing starting with 7 indicates that this drawing shows an all new part which is not interchangeable with the earlier version. This jacket is intended to be used with the late style two piece booster cap/bearing assembly which retained the bipod head with locking "clip" rather than the earlier snap ring style retainer.
Right: This drawing isn't a drawing at all, it's a list of the parts of the M1919A4 and M1919A5 which are required to be marked. It also contains a list of the manufacturers identification marks. Note that only three of the listed manufacturers actually made M1919s . Under the component list line 14 and line 18 are blank. Originally these lines contained the rear sight spring on line 14 and the alternate design of that spring on line 18. Revision 8 dated 7-22-43 to this drawing removed the requirement that these parts be stamped with the manufacturers identification. The list of manufacturers may have been a generic list created prewar because Ordnance didn't know which companies would be making M1919's the date on the original drawing is April 7, 1941 8 months before the U.S. declared war.
                         Click on image to see full drawing.

Click on image to see full drawing.

Sheet 12 of the 1942 Base Shop Data book for the 1919A4 Overhaul section outlines the prescribed method of aligning the barrel jacket with the "receiver" (casing).

This alignment operation consisted of placing the casing with the barrel jacket and front bearing attached in an alignment fixture checking alignment with gauge "C" (shown on drawing C16315) and if required " Withdraw from alignment frame and, grasping the receiver, strike the barrel jacket sharply on a lead block on opposite side to the binding surface. Replace in alignment frame and check with gauge C. Follow this procedure until perfect alignment is secured." Gauge C is a sort of mandrel passed through the rear of the casing with alignment surfaces for the front barrel bearing, attached to the barrel jacket, and the rear barrel bearing in the trunnion.

Somehow this procedure, which falls under the category of "If it doesn't fit, find a bigger hammer" school of machine shop operating practice, is not nearly as technologically advanced as I expected it to be. I thought there would be some big press that would straighten out the whole works. I was wrong. Basically, the Armorer beat the jacket into alignment.

Sheet 11 of the Dismantling section of this same BSD has a note "These jackets are not interchangeable and should be kept with the original receiver" This may be one of the reason that the practice of sweat soldering the jacket to the trunnion was initiated. Sweating the parts together would preclude the jacket being separated from the casing during casual disassembly. Sweating would also prevent the jacket from unscrewing itself in the event that the locking screw fell out.

The air-cooled barrel jacket is nothing more than a steel tube with internal threads at both ends, the casing end having a longer threaded portion, a hole for the jacket locking screw, and the muzzle end having a notch for staking the front barrel bearing/ booster locking band with holes for air circulation to assist in cooling the barrel itself. The drawing C62503 shows a 19.08 inch length for the M1919A4 jacket which remained unchanged from the adoption of the 24 inch barrel until the end of production. Drawing C62503 Revision 9 dated 5-10-48 changed the drawing number to (C) 5562503 and part number (piecemark) to 5562503. The earliest versions called for seamless tubing, but this requirement was changed by Revision 6 dated 6-18-42 to allow tubing with an electrically welded seam.

Left: This drawing is from SNL A-6 (Standard Nomenclature List) dated September, 1943 and shows the barrel group parts for the A4 and the early A6. The development of the 1919A6 starting in late 1942 required a completely different barrel and a slightly modified jacket design because of the addition of the bipod head. The bipod head mounting required a longer booster/bearing. Early A6's used a shorter barrel jacket, C93962 (16.594 inches long) to accommodate the length of the B261109 one piece bearing/booster which supported the bipod head which was secured in place using the A238235 (snap) ring. The A4 barrel group parts, other than the development of a one piece bearing/booster and Stellite barrels remained virtually unchanged until production ended. July 22, 1943 seems to be the date of the A6's official adoption as that is the original drawing date on most of the A6 drawings.
Right: This drawing from ORD 9 SNL A-6 dated April, 1947 shows the late type A6 barrel group parts. Note that all of the parts except for the locking band A170491 have different drawing numbers from the previous illustration. This barrel group uses a different, even shorter jacket, Stellite barrel, two piece front bearing/booster cap, and bipod head retaining parts. These parts, other than the band and barrel, are NOT completely interchangeable with the earlier parts. The same document lists two different A6 casing assemblies D35358 "for guns of early manufacture" and D7114037 for the later style. The "7" prefix on the (D)7114037 drawing indicates non-interchangeability as it is a post 1943 "new" part/ drawing number.

The only difference in the component parts of the different casing assemblies is the barrel jacket, and a typographical error in the list of components for the late style D7114037 casing assembly that incorrectly describes the A20527 breech cam block screw as a rivet. The C7160455 jacket which was the final A6 jacket design was adopted on March 21, 1944 and it is 15.954 inches long.

Another confusing aspect of M1919 barrels is the term "Stellite barrels". Stellite is the trademarked name of a nonferrous, cobalt-chromium alloy often combined with various other materials to produce the exact alloy required. It was developed by Elwood Haynes in the early 1900's. The trademark name "Stellite" is the property of the Deloro Stellite Company. Stellite alloys come in a variety of compositions depending on their intended use. One common use for Stellite was valves, valve guides and valve seats in internal combustion engines. Some Stellite alloys have high melting points, and extremely high wear and corrosion resistance making them very useful for applications like a machine gun barrel.

Because of Stellite's wear resistance it is difficult to machine, usually the part is cast to near finished dimension and ground to final specifications. Parts made from Stellite are expensive to produce, however, by using the Stellite parts in in high temperature/wear areas in combination with other less expensive and more easily fabricated materials like steel, the useful life of the assembly can be extended several times. The bore area just ahead of the chamber of a machine gun is subject to repetitive intense heat and friction, and in addition, prior to about 1954 when the U.S. Army's primer composition changed, caliber .30 weapons were also subject to the corrosive effects of hydroscopic salts produced by primer ignition.

Ordnance began experimenting with Stellite barrel components for the Cal. .50 BMG in 1942, however, progress on developing and adopting Stellite for barrel use dragged on until 1944 when a workable process to produce a Stellite bore liner for the Cal. .50 BMG was developed. This liner, in combination with nitriding and chromium plating the bore and exterior bearing surfaces produced barrels that had a useful service life 300% greater than standard barrels.

Since excellent results had been obtained using the Stellite/nitritrided/chromium plated Cal. .50 barrels it was decided to apply a similar process to Cal. 30 barrels for the M1919A6. The A6 was chosen, because it's lighter barrel, it weighed about 4.8 lbs versus the A4 barrel weight of 7.47 lbs. caused it to wear faster than the A4 due to it's inferior heat dissipation ability. The decision to make Stellite barrels the preferred A6 type was not reached until July of 1945, this would preclude very many, if any, Stellite A6 barrels from service use during WWII.

The earliest type of Stellite A6 barrel is shown on drawing D7162295. This drawing is of a barrel assembly consisting of the liner (the Stellite bore insert) C7162479, retainer (the steel chamber insert) B7162480, the tube ( the steel barrel itself) D7162478, and a pin which held the retainer in place, BFDX1. Note that all of the parts other than the pin, a standard part, have successive drawing numbers. The barrel was only available as an "assembly". The individual parts making up the assembly were not. This early type barrel assembly did not have a chrome plated front barrel bearing and chrome plated bore ahead of the liner.

Stellite barrels can be easily identified, other than looking at the part number imprinted on the barrel, by carefully examining the chamber end. The seam between the steel retainer and the barrel tube is clearly visible.

The first mention of a Stellite barrel assembly for the A4 that we could find is in ORD 7 SNL A-6 dated October 1951. This lists the assembly drawing as D7162785. Changes No. 1 to this document dated February, 1952 still shows the D35233 (now called 6535233) standard A4 barrel and the D54559 (now called 6554559) the standard A6 barrel with a note that the standard barrels were to be issued until the supply was exhausted and only then would the Stellite types will be issued. This seems to make sense, since the Army, most likely had, literally, tons of the standard barrels on hand and was wont to not waste anything in a tight budget post war era.

Photo courtesy of Tom Pfremmer
Many A4 and A6 Stellite barrels were also paint stenciled in addition to being imprinted with part, or in this case drawing/part numbers on this last model RIA A6 barrel. Even though Ordnance started to implement a 7 digit drawing/part/stock number system in 1943, the habit of using the drawing size letter that was supposed to be eliminated with the all digit system died hard. The reason for this is the drawings were still prepared on the various letter sized sheets originally mandated in 1922.
Left: This picture shows the part number of the final version of a Stellite 1919A4/M37 barrel produced by SAK (Saco-Lowell Shops, Saco/Biddleford, ME.). Saco produced not only Stellite A4/M37 and A6 barrels but also complete purpose built M37 BMG's all of which left the factory with Stellite barrels. RIA also produced purpose built M37's and Stellite barrels for both the A4/M37 and the A6. The M37, the replacement for the M1919A4 Fixed, M1919A4E and the 1919A5, was the last of the Cal. .30 air cooled BMG's. This particular barrel has no ordnance flaming bomb markings. It does have the chrome plated bore ahead of the liner and chrome plated front bearing surface. Saco-Lowell was an old line New England manufacturer of machinery for the textile industry before receiving an Ordnance contract to produce M37 BMGs and parts.

Photo courtesy of Tom Chial
The end of an era.

Photo courtesy of Tom Pfremmer
Right: This barrel marking is from an RIA A6 barrel, the significance of -G following the part number is unknown. It may be a production code assigned by RIA to identify which production line produced it. This is the same A6 barrel with the paint stencil shown previously.

Click on image to see full drawing.
Drawing (D) 7162295 dated September 12, 1945 shows the parts of a first type Stellite barrel assembly for the M1919A6. September 12, 1945 is 10 days after the Japanese signed the surrender documents aboard the USS Missouri in Tokyo Bay. The Stellite "liner" was held in place by the "retainer" actually a chamber insert which was screwed into the "tube" and locked in place by the pin driven in from the rear. Notes on this drawing require stenciling this assembly "D7162295 LINED ASSY." in inch high letters with heat resistant white paint, a practice that was continued on the later 7418400 A6 and 7418399 A4 Barrel assemblies that had chrome plated bores ahead of the liner and chrome plated front barrel bearings.

Click on image to see full drawing.
Drawing C 7162479 dated September 12, 1945 shows the Stellite liner which is 5.250 inches in length. Apparently there were 5 different outside diameters for this part starting with .5010 and increasing in diameter by .0005 increments to a maximum diameter of .5030. Notes indicate "USE SELECTIVE ASSEMBLY TO OBTAIN SHRINK FIT SHOWN ON DRG. D7162295" which is the previous drawing of the barrel assembly. There is also a note explaining that "RIFLING MAY BE DONE AFTER ASSEMBLY' and a detail drawing of the standard 4 groove, 1 turn in 10 inches, right hand twist .30 caliber rifling. Note the shoulder on the Stellite casting .750 inches from the chamber end which butted against a matching cut in the bore of the barrel preventing the liner from moving during firing.

Photo courtesy of Chris Ott
Left: This photo shows a late A6 Stellite barrel complete with original packaging. The cardboard tube with sleeve end, original VCI wrapping paper and a VCI wick for the bore. VCI is the acronym for volatile corrosion inhibitor a chemical compound that gives off vapors that protect against rust. Anyone who has purchased a Smith & Wesson firearm in the '70s has seen the piece of brown paper with the blue S&W logos placed in the box this is VCI paper. Some manufacturers of reloading dies also include a small piece of VCI paper in the die box .

Previous to the adoption of VCI packaging, barrels were filled and coated with Cosmoline and wrapped in Kraft paper. Various other packaging schemes were used over the years, including a lightweight cardboard tube over wrap with the ends stapled closed. Ordnance even developed a wooden crate for quantity shipment of replacement barrels.

Left: Close up of the label on the shipping container pictured above. The 9/62 date indicates that that there was still an need for A6 parts into the 60's.
Photo courtesy of Chris Ott.

Instead of changing the name of a company that GM acquired, like Saginaw Steering Gear or AC Spark Plug, GM corporate policy was that they just added "Division Of General Motors" after the original name.

Barrels markings indicate that some barrels were manufactured by Guide Lamp under subcontract from Saginaw and some were produced under direct contract. Guide Lamp is also famous as the manufacturer of the Cal. .45 "Liberator" single shot throw away pistol made from sheet metal stampings, and the sole WWII manufacturer of the M3 and M3A1 "Grease Gun" submachine gun. The Anderson, IN plant was last operated as a Delphi Automotive production facility.

This is a D35233-14 double marked with the Saginaw (SG) and Guide Lamp (GL) imprints. Guide Lamp, located in Anderson, IN was a Division of General Motors Corporation.
                                 Photo courtesy of Rollin Lofdahl

Photo courtesy of Rollin Lofdahl

Left: This D35233 RIA produced barrel has the number 44 stamped on the muzzle end. The significance of the marking is unknown, it is possible that this number indicates the year of manufacture, 1944, but the D35233 barrel design was superseded by D35233-6 barrels on 10-03-1940 and it is not likely that RIA, who was the "in charge" ordnance facility for M1919 production, would be producing designs superseded 4 years earlier.

The M1919's being air cooled weapons consumed barrels at a prodigious rate. Each machine gun squad was required to have at least one spare barrel, carried in a canvas bag along with other repair parts, such as a complete bolt assembly and a barrel extension while in the field.

This canvas bag for the barrel is officially known as Cover, spare barrel, M9 its drawing number is D30674. The earliest versions was made of "ol-db" (olive drab) cotton duck with a snap closure and was either lined with latigo leather, or as an alternative, asbestos cloth. Apparently, the asbestos barrel changing gloves and the asbestos lined spare barrel cover were not considered health hazards at the time. Later versions of the barrel cover dispensed with the lining

SNL A-6 dated May 28, 1941 is the earliest SNL for the M1919A4 that we have encountered, although it states that there was at least one earlier version, dated December 1, 1939, published. This SNL is entitled "Parts and Equipment" and is one size fits all document that lists not only repair parts and assemblies for the M1919A2, M1919A4 Fixed and Flexible and the M2 Tripod but such oddities as the Machine Gun Hanger M3 and the Ammunition Hanger M8 . These two items are for pack transporting the weapon, accessories, and ammunition on horses.

This SNL states that during twelve months in a theatre of operations 400 barrels are required for the maintenance of 100 M1919A4's. Additionally it lists the required spare parts, accessories, ammunition boxes, cleaning equipment, ammunition belts, canvas goods, belt filling machines, special purpose tools along with the weight of the required items for "Combat Vehicle and Train Defense Units (Horse or Mechanized)".

Remember this was 1941 the Army still had a few horses, but the "Train Defense Unit" is a new one on me. Must be something left over from WWI.

One of my Uncles, Charles Fassola, entered the Army in 1939. Chuck, a steam fitter in civilian life, was assigned to a Ft. Reilly, KS Cavalry outfit that was still horse mounted. At one time I remember seeing a picture of him, mounted on a horse, complete with Patton saber, rifle in a scabbard, riding pants with suspenders, boots, and a campaign hat. He looked like something out of the movie "The Wild Bunch" wish I had the picture.

Starting with SNL A-6 published in 1943 the plethora of information contained in the 1941 SNL A-6 was divided into three separate booklets, List of All Parts, Organizational Spare Parts, and the Addendum which listed major items, maintenance parts and equipment available. This last publication was intended for use by Ordnance personnel only.

By 1944 these booklets were assigned publication number prefixes which identified the nature of and the intended audience for the contents. ORD 9 SNL A-6 replaced the list of all parts, ORD 7 SNL A-6 replaced the organizational maintenance allowance, and ORD 8 SNL A-6 became the field and depot maintenance allowances references. This method of identifying publications continued into the early 1960's when a new series of Technical Manuals combined everything back into one reference source. TM9-1005-212-25, dated 28 May, 1969, replaced all of the publications listed above and then some. This Technical Manual covered the M1919A4, M1919A6, and the last of the breed the M37 along with the M2 tripod.

By this late date, the A4 and A6 being in semi-retirement in some Army Reserve and National Guard units having been replaced by the M60 GP machine gun starting in 1957, only Stellite lined barrel assemblies were available. This document calls for a 15 day maintenance allowance of 2 barrels per 100 weapons and a one year contingency allowance of 36 per 100 weapons.

There you have it, my take on barrels and a few other things. My sincere hope it that you found this article both useful and entertaining.


Rock Island Arsenal Museum, Jodie Creen Wesemann, who supplied all of the Ordnance drawings, and Ordnance Publications quoted. Without Jo's generous help and unfailing patience, we would still be guessing about happened and when it happened.

Rollin Lofdahl, a good friend, and knowledgeable guy who has been much help in deciphering all of this. Rollin is my Technical Editor, which means he provides information, encouragement and most important, the very necessary sanity checks on what I commit to paper.

A special thanks to the members of the forum, and the forum founder "Shots" who help with pictures, encouragement and really odd finds. They are the eyes and ears of this effort.

Photos are individually credited, those lacking a credit are the authors.

Hard Rain, History of the Browning Machine Guns, Frank Iannamico, Moose Lake Publishing, LLC

The Browning Machine Gun Vol. 1, Dolf L. Goldsmith, Collector Grade Publications, Inc.

World War I, S.L.A. Marshall, McGraw-Hill Inc.

U.S. Infantry Weapons of WWII, Bruce N. Canfield, Andrew Mowbray Publishers

Standard Catalog of Military Firearms, Phillip Peterson, Editor, Gun Digest Books