Just to add on to what Clandestine is saying, the H&K 416 (arguably a starting point for the recent gas piston AR phase) was designed to meet a very specific set of requirements: reliable suppressed operation from a variety of barrel lengths using a variety of ammunition (different bullet types, velocities, pressures, etc). Increased weight, wear, and parts replacement were expected, and those tradeoffs were considered acceptable for having a weapon that would be effective and reliable with the stated requirements. Larry Vickers has gone on record stating this, and multiple alum from the organization that spawned the 416 have concurred with this. And most that I personally know agree that a DI AR pattern rifle is all around better for most purposes.
My critique often makes me a target, so I have to minimize what I share.
People believe the propaganda about the D.I. and are convinced or duped into believing G.P. is an improvement.
They ignore the things that had to be grought to market to fix the problems G.P. AR systems create like faster unlocking and bolt breakage, especially with a suppressor (fluted Chambers, roller cams, and adjustable gas), carrier tilt (beefed carrier tails and modified receiver extensions), carrier key breakage (monolithic carrier and key).
The bolt breakage issues has much to do with bolt load when unlocking. G.P. AR designs add more bolt lug load due to the way it works. D.I. removes load when unlocking, which reduces bolt stress.
Personally I like well made DI ARs and well made piston ARs, but if I could only pick one I would 100% go with a DI AR/M16 derivative. That said there are plenty of non-AR firearms designed from the ground up around long stroke and short stroke piston gas systems, and they work great. Like AK pattern rifles, which are a design that Clandestine also loves dearly and never disparages.
