Modern Arms

 

 

Dan Baum

 

Military Rifle Basics:

 

Gas and delayed-blowback operating systems are the only ones suitable to modern, auto-loading military rifles. Recoil-operated rifles, with their moving barrels and required bearing surfaces, don’t work well in the field. The Maxim and Vickers heavy machineguns (water-cooled, recoil-operated) ran well during WWI, but recoil operation ultimately proved inferior to gas operation, particularly in light machineguns.

 

Multi-lug, rotating-bolt locking systems (M4) are the most inherently (academically) accurate. Tilting-bolt rifles (FAL, Bren) are the least inherently accurate. Large-lug, rotating-bolt rifles (AK, M14, XCR) are in the middle. However, “accuracy” is a relative term, and all rifles mentioned herein are more than accurate enough for serious purposes.

 

Rotating-bolt rifles (gas operation) typically open under low pressure, as the bullet has long-since cleared the muzzle, so small, delicate extractors usually suffice. Rotating-bolt rifles are also the only ones that feature “slow, initial extraction,” which contributes to reliable extraction, and subsequent ejection of empty cases.

 

Gas-operated rifles sometimes feature a gas-diversion system that is “user-adjustable.” User-adjustable gas-diversion may be arguable with rifles chambered for 7.62×51. Mostly unnecessary in rifles chambered for 5.56×45. The inherent problem is, of course, that anything in military usage that can be “adjusted” at the user-level, will be perpetually misadjusted!

 

With gas-operated rifles, hot gas that is diverted into an expansion chamber (and subsequently pushes the piston and op-rod backward against spring pressure) is full of dissolved carbon, so after diverted gas has done its job, it must be subsequently vented to the outside without delay. As gas cools, carbon will come out of solution, and we want that to happen when it is all clear of the rifle.

 

Inherent to roller-delayed blowback (PTR91, Marcolmar CETME/L, also lever-delayed blowback, eg: French FAMAS) rifles is a precipitous, sharp jerk on the case-head. Accordingly, these rifles mostly feature large, heavy extractors and “fluted” chambers, which aid in releasing the case from chamber walls. These rifles typically start to open when there is still some pressure within the barrel, so bolts and bolt carriers tend to get dirty.

 

This is because with “fluted” or ‘scored” chamber walls, there is significant gas leakage backwards into the receiver (which is unavoidable). This gas is not immediately vented while it is still hot (as is the case with gas-operated rifles). So, when this gas has an opportunity to cool while it is still lingering within the receiver, dissolved carbon precipitates-out rapidly, coating bolt, bolt-carrier, and other parts, as noted above.

 

Roller-delayed blowback rifles still enjoy an excellent reputation for reliability and continue in widespread use, but weight is a problem, even in 5.56×45 caliber. They are heavier than comparable gas-guns, and for that reason have fallen-out of favor with Western militaries.

Roller-delayed blowback and tilt-bolt rifles (G3, FAL) were popular with military users of the last Century, because these systems readily lent to themselves to the use of stamped receivers and thus to mass production. Today, polymer has largely replaced stampings.

 

Roller-delayed operating systems do not work well with suppressors, owing to significant back-pressure inherent to most suppressors.

 

Until we’re shooting charged particle-beam weapons, the foregoing technology will have to suffice to keep us all from harm!

 

We need these modern weapons, and we need know how to keep them and run them to their maximum effect.

 

Arm yourself while you still can. Western Civilization is unraveling far faster than most of us can comprehend!

 

 

Freeman Dyson

 

/John