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4 Aug 2014 - mkillebrew

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FAL STG-58 - 7.62x51

The FAL is a gas-operated tilting locking bolt with a short-stroke gas piston in 7.62x51. The gas from the fired round is bled off at the adjustable gas block where excess is vented. The gas pushes the piston to the rear against the force of the piston spring. The gas piston pushes on the top of the face on the bolt carrier which engages the bolt's lugs against the ramping sides inside the carrier while recoiling, pulling the rear of the bolt along a track and allowing it to slide off the block in the carrier and rise into it, unlocking from the shoulder. The top of the rear of the bolt then engages the inside of the bolt carrier on the edge of the lug that pushes the bolt down onto the shoulder, and under impulse of recoil, fully moves the bolt and bolt carrier to the rear. The tail on the bolt carrier moves into the buffer tube against the buffer spring, cocking the hammer. The ejector moves through a groove on the bottom of the bolt before moving through the bolt face and ejecting the brass. On forward movement initiated by the buffer spring, the bolt strips a new round from the magazine and chambers it. At this point the bolt is fully forward and unlocked with the carrier still slightly to the rear. When the carrier continues forward, the rise in the top of the carrier acts on the rear of the bolt, forcing it down and against the locking shoulder which is situated just behind the ejector. The fire control group of the FAL is fairly simplistic as it could function in both semi-auto and full-auto without the selector, which simply restricts movement of the trigger. If pulled only slightly, which semi-auto position allows, the disconnector is caught by the notch on the hammer, and upon releasing the trigger, it pushes the disconnector over the edge of the top of the trigger, giving it the necessary clearance to disengage the hammer and release upon pulling it again. Pulling the trigger further, which is what the auto position allows, disengages the disconnect fully, allowing the safety sear, which is not pictured here, to be the only engagement on the hammer. The firing pin is spring loaded and helps to secure to bolt to the bolt carrier when removed from the receiver. When the last round is fired, the magazine floorplate pushes the bolt lock up, and catches the bolt. The bolt can then be released by pushing down on the bolt latch when a charged magazine is inserted. Headspace is directly related to the size of the locking shoulder, which unlike other tilting locking bolt rifles, is easily interchangable.

Right Side:

Left Side:

Receiver - Right Side:

Receiver - Left Side:


Gas Plug Left - Gas Regulator Right:

View Inside Ejection Port - Bolt Open:

Magazine Catch Left - Bolt Lock Right:

Trigger and Selector:

Rear Sight:

Mag Well - Underside of Bolt Group:

Charging Handle:

Receiver Group Broken Open:

Receiver - Top Cover Removed - Notice Cocked Hammer and Firing Pin:

Receiver Above - Hammer Cocked:

Receiver Above - Hammer Released:

Receiver Cover:

Ejector and Locking Shoulder at Right:

Bolt Face:

Bolt Group - Side:

Bolt Group - Locked:

Bolt Group - Unlocked:


Bolt Carrier - Underside:

Bolt Carrier - Inside - Note Ramp That Acts On Bolt's Ears:

Bolt Carrier - Inside - Note Rise in Bolt Carrier Top that Pushes Bolt Rear Down:

Bolt - Rear - Ears which Engage Ramps Inside Bolt Carrier:

Bolt - Rear - Locking Shoulder Engagement Surface:

Bolt - Rear - Surface that Engages Bolt Carrier on Recoil:

Receiver Pivot Screw - Removed:

Lower Receiver - Complete:

Hammer Spring:


Locking Plate:


Trigger with Spring Loaded Disconnector:

Lower Reveiver - Stripped:

FCG - Removed and Aligned:

Breech Face:

Gas Piston, Return Spring and Plug:

End of Gas Piston and Plug:

Upper Receiver - Piston Recessed:

Upper Receiver - Piston Rearward:

Barreled Upper Receiver:

Gas Tube Assembly:

Recoil Buffer:

Lower Receiver - Buffer Tube and Stock Removed:

Lower Receiver - Buffer Tube - Buffer Spring:


7.62x51 Rounds:

STG-58 - Oblique View with Battle Load: