The FAL operates by means of a gas-operated action very similar to that of the Russian SVT-40.
The gas system is driven by a short-stroke, spring-loaded piston housed above the barrel, and the locking mechanism is what is known as a tilting breechblock.
To lock, it drops down into a solid shoulder of metal in the heavy receiver much like the bolts of the Russian SKS carbine and French MAS-49 series of semi-automatic rifles.
The gas system is fitted with a gas regulator behind the front sight base, allowing adjustment of the gas system in response to environmental conditions.
The piston system can be bypassed completely, using the gas plug, to allow for the firing of rifle grenades and manual operation.
The FAL's magazine capacity ranges from five to 30 rounds, with most magazines holding 20 rounds.
In fixed stock versions of the FAL, the recoil spring is housed in the stock, while in folding-stock versions it is housed in the receiver cover, necessitating a slightly different receiver cover, recoil spring, and bolt carrier, and a modified lower receiver for the stock.

For field stripping the FAL can be opened.
During opening the rifle rotates around a two piece pivot lock and pin assembly located between the trigger guard and magazine well to give access to the action and piston system.
This opening method causes a suboptimal iron sight line as the rear sight element is mounted on the lower receiver and the front sight element of the sight line is mounted on the upper receiver/barrel and hence are fixed to two different movable subassemblies.
The sight radius for the FAL 50.00 and FAL 50.41 models is 553 mm (21.8 in) and for the 50.61 and FAL 50.63 models 549 mm (21.6 in).

FAL rifles have also been manufactured in both light and heavy-barrel configurations, with the heavy barrel intended for automatic fire as a section or squad light support weapon.
Most heavy barrel FALs are equipped with bipods, although some light barrel models were equipped with bipods, such as the Austrian StG58 and the German G1, and a bipod was later made available as an accessory.

Among other 7.62×51mm NATO battle rifles at the time, the FN FAL had relatively light recoil, due to the user-adjustable gas system being able to be tuned via a regulator in fore-end of the rifle, which allowed for excess gas which would simply increase recoil to bleed off.
The regulator is an adjustable gas port opening that adjusts the rifle to function reliably with various propellant and projectile specific pressure behavior, making the FAL not ammunition specific.
In fully automatic mode, however, the shooter receives considerable abuse from recoil, and the weapon climbs off-target quickly, making automatic fire only of marginal effectiveness.
Many military forces using the FAL eventually eliminated full-automatic firearms training in the light-barrel FAL.
The FAL operates by means of a gas-operated action very similar to that of the Russian SVT-40. The gas system is driven by a short-stroke, spring-loaded piston housed above the barrel, and the locking mechanism is what is known as a tilting breechblock. To lock, it drops down into a solid shoulder of metal in the heavy receiver much like the bolts of the Russian SKS carbine and French MAS-49 series of semi-automatic rifles. The gas system is fitted with a gas regulator behind the front sight base, allowing adjustment of the gas system in response to environmental conditions. The piston system can be bypassed completely, using the gas plug, to allow for the firing of rifle grenades and manual operation. The FAL's magazine capacity ranges from five to 30 rounds, with most magazines holding 20 rounds. In fixed stock versions of the FAL, the recoil spring is housed in the stock, while in folding-stock versions it is housed in the receiver cover, necessitating a slightly different receiver cover, recoil spring, and bolt carrier, and a modified lower receiver for the stock.
For field stripping the FAL can be opened. During opening the rifle rotates around a two piece pivot lock and pin assembly located between the trigger guard and magazine well to give access to the action and piston system. This opening method causes a suboptimal iron sight line as the rear sight element is mounted on the lower receiver and the front sight element of the sight line is mounted on the upper receiver/barrel and hence are fixed to two different movable subassemblies. The sight radius for the FAL 50.00 and FAL 50.41 models is 553 mm (21.8 in) and for the 50.61 and FAL 50.63 models 549 mm (21.6 in).
FAL rifles have also been manufactured in both light and heavy-barrel configurations, with the heavy barrel intended for automatic fire as a section or squad light support weapon. Most heavy barrel FALs are equipped with bipods, although some light barrel models were equipped with bipods, such as the Austrian StG58 and the German G1, and a bipod was later made available as an accessory.
Among other 7.62×51mm NATO battle rifles at the time, the FN FAL had relatively light recoil, due to the user-adjustable gas system being able to be tuned via a regulator in fore-end of the rifle, which allowed for excess gas which would simply increase recoil to bleed off. The regulator is an adjustable gas port opening that adjusts the rifle to function reliably with various propellant and projectile specific pressure behavior, making the FAL not ammunition specific. In fully automatic mode, however, the shooter receives considerable abuse from recoil, and the weapon climbs off-target quickly, making automatic fire only of marginal effectiveness. Many military forces using the FAL eventually eliminated full-automatic firearms training in the light-barrel FAL.
FN FAL