That’s a strange title for an article, isn’t it? Odd as it may sound, if it weren’t for the prolific use of the rifle grenade in the Second World War, the virtues of adjustable gas systems likely wouldn’t be realized.
If your reaction to the above statement is bewilderment, stay with me, I’ll explain.
Sound suppressors function like a muffler for guns. They do this by slowing the expansion of hot gasses escaping through the muzzle of a freshly fired firearm. But, there’s no free lunch, and suppressors are no exception.
By delaying the escape of hot gasses, suppressors force these excess hot gasses back inside the firearm itself. This has two negative side effects.
First, it increases the speed with which the gun becomes fouled because the hot carbon-filled gasses that normally fly out the muzzle instead are pushed back inside the gun.
Secondly, the deceleration of these gasses, drastically increases the backpressure of the internal gasses, thus operating the gun at a much higher velocity than intended. This wears the components of the gun extra quickly, and in many cases, operates the action too quickly for the magazine spring to keep up. This causes a failure to feed in over-gassed guns.
OK, but what does the rifle grenade have to do with any of this?
Rifle grenades are explosives (or sometimes less-lethal options like flares or tear gas) that are fixed to the muzzle of a rifle, and use the pressure of a blank round to propel them roughly a hundred yards or so.
They first found widespread use during the Great War, where their indirect fire capabilities made them invaluable at routed entrenched infantry. More modern versions were developed for use as anti-vehicle or light armor weapons.
These medium-range explosives were a tremendous improvement over hand-thrown bombs, but they put undue wear on the rifle used to launch them. Now, they worked great on manually-operated firearms, but with the introduction of semi-automatic firearms, some countries needed to adjust the pressure levels of their self-loading guns to maximize the effective range of these rifle-launched grenades.
While no firearms historian (that I could find during my research) has directly linked the development of adjustable gas systems to the widespread use of rifle grenades, it does stand to reason, since every automatic military rifle from around the end of World War 2 with an adjustable gas system has a rifle grenade setting.
If that’s the case, then suppressor fans should thank their lucky stars for rifle grenades. Imagine having to get special buffer springs, bolt carriers, or ammunition to properly run your favorite suppressor host with a can. Sure, direct blowback guns would be largely unaffected, but that means larger-caliber rifles and carbines wouldn’t be able to function as reliability with suppressors. Now, if we could only get the military to integrate an adjustable gas system into the M4….