Back to main FN pageFN30 series ground MGsModele 1932 aircraft MGParts comparison  of variantsFixed and flexible backplatesArmorer's kits, etc.FN30 semi-auto buildFN mounts and cradles
As with every other aspect of the Brownings, Fabrique Nationale made refinements and simplified some details of the back plate design. The single handled back plate appeared in an early US Browning aircraft MG, but was refined by FN and remained the primary flexible back plate throughout the .30 caliber's production, both in ground and aircraft weapons.
Left: Modèle 1932 flexible back plate with vertical buffer. At right is a US ANM2 vertical buffer showing the internal parts. The basic principle of the assembly is the horizontal force acts on the the angled buffer plate which transfers the force 90 degrees to the two angled brass plates. It is more efficient to have the forces act in a straight line, which is why this system evolved into the horizontal buffer on later models.
Left & Right: The Modèle 1938 flexible back plate with vertical buffer. The horizontal buffer employed a spring and a split brass collar & steel cone. The drawing below, right, shows the component and the principle. The bolt imparts a force on the buffer plate, which in turn transfers this force to a cone, causing the split brass collar to expand against the sides of the buffer tube so friction can arrest the rearward movement. A heavy spring returns the plate, cone, and ring back to their static positions.
Spade grips appeared in the 1950s on the the Modèle 1952. They employed a horizontal buffer with the cone and split ring components described above. The design is considerably more straight forward than the ANM2 spade grips, and featured a safety of unique design. Note the buffer screw on the spade grips. Unlike the internal screw on the US ANM2 spade grip buffer, the FN uses a heavier screw with an external component which has the same diameter as the buffer tube.

The trigger is shown above both from the shooter's perspective and from the side. The part shaded in green is the safety.
The function of the safety can be seen in the photo at right. The left image shows the safety in the "on" position with the notch (blue) resting on the lower edge of the upper handle bracket. The shooter, with thumbs on the trigger spade, uses the tips of his two index fingers to pull back on the safety spade, causing the notch to lower and release. It's actually more of a pinching action between the thumbs and index fingers. To reset the safety, you simply pull back on the trigger spade with your index fingers, flexing the trigger linkage, and the spring loaded safety pops into place. The trigger reaches the end of its travel before the safety can engage so that it does not inadvertently do so during firing.
The fixed back plates are simply the buffer housings and firing bellcrank without the handle assemblies. On the top of each you
can see a small rectangular opening (red arrow) which provide access to the bellcrank so the solenoid can fire the gun.

In the photo on the left two types of solenoid are shown. The hydraulic (on the left), and the pneumatic. The hydraulic solenoid is made of steel and quite heavy, whereas the pneumatic solenoid is made primarily of aluminum and is very light weight. Each fires the gun from a different point of entry. The hydraulic solenoid has an arm which enters the receiver through the trigger bar opening and pushes directly on the sear. The pneumatic solenoid enters the top of the buffer and depress the bellcrank which lifts the trigger bar. Perhaps the heavier hydraulic solenoid is needed to overcome the stiffer resistance of the sear, as it does not have the advantage of the trigger bar lever. You may have your own thoughts on this.

Both styles of solenoid fit in the sight base rails. In the photo on the left the arm is raised. On the right the arm is lowered into the bell crank slot. The arm is released by pulling the knob (red arrow) to the left.
The hydraulic solenoid can be installed from the front of the sight base rails, or by inserting the actuator (red arrow) and then sliding the solenoid in from the rear to meet it. When the cross pin in inserted through the rearmost hole (green arrow) it passes through the hole in the actuator shown below.

Solenoid actuator.