bmg17a1 wrote:There are lots of variables between the 74 and the 42 that would need consideration and understanding to make any meaningful comparison, but in my opinion, such comparisons are generally meaningless anyway. Seat of the pants differences in feel just between 42s can be downright amazing. The .308 42/58 is smooth as butter compared the 7.92 guns, and more so than the 74. I like the physicality of the 42 types and enjoy the ride.
I've often opined that, like any roller locked gun, it is the unique contact angle of any unique locking wedge facing any given roller that controls the personality of the gun. The entire roller locking concept, being an unlocked delayed blow-back action, is entirely dependent upon the absolute part-to-part consistency of the angular relationships of resistance. That any 2 guns would "feel" and thus be responding to the recoil impulses differently is entirely consistent with the notion of simple differential wear of the parts....rollers, locking recesses, face angle of the locking wedge, etc., that with each minute variation results in a new synergy of the entire system.
The "feel" part of shooting these guns is largely due to the unique pathways taken of the transmitted recoil forces as they progress through the angular translations of the locking parts. Change, alter, or modify any one pathway even slightly, say, from an asymmetrically worn locking wedge face, and that gun now will display a unique recoil as it does not match anymore the carefully calculated pathways of force that appeared on the designers original sketches. Bolt rollers are troubling in that they wear down with use. Same for the locking recesses in -some- barrel extensions. A lot of this is exacerbated by another of the synergy parts, the recuperator assembly, being ignored as it suffers the effects of aging and use, too. Lose any of the original force balancing inherent in new parts....and synergistically the problems will manifest themselves in the other effected areas.
Point being here is that all of the locking system parts contribute to the "feel" of the recoil impulse, and that it is likely hard to compare any two guns as Bob says. Given a range of different guns, all that really matters is that any unique set of locking system parts perform well ENOUGH to keep the margins of safely intact, breech pressure safely contained, unlocking dwell within safe periods, etc. If the locking forces are too well contained the gun will run "rough" as it takes comparatively more absolute force to cause the rollers to disengage, if the locking system parts allow unlocking to begin too soon- from worn, incorrect, or improper parts used...Bad Things(tm) can happen. One of the things about a "smooth" running gun is that it shows a nearly perfect balance (currently) exists in the synergy of the locking system component parts.
That a MG-42 running .308 ammo will seem "smoother" than the same gun running 8mm is not strange as the original design of the locking system synergy for the recoil impulse of the 8mm cartridge's peak pressures (which one must intimately understand was TOTALLY relevant to the GERMAN'S idea of their own proprietary propellants and attendant properties only) was intended to be balanced for the lower absolute impulse of their cartridges compared to the later 7.62 NATO M80 round. An important realization is to remember that the whole reason the initial development of the T65 cartridge came about was due to a discovery of how to better prepare propellant formulations for energies relative to bulk. IOW's the newer propellants contained similar energies as earlier propellants in a form that had less physical bulk. That chemical property change, resultant in differing deflagration characteristics, is what makes recoil impulse of the 7.62 NATO give different operating "feel' through the locking system.