Quote Originally Posted by BPTactical View Post
Generally true- but I have worked on two rifles that had lack of gas flow issues that resulted in very sharp and erratic cycling. One rifle was a late manufacture Bushy that had the gas port drilled off center on the bolt carrier and the other was a gunshow special of unknown pedigree that had a FUBAR gas key. Both rifles cycled erratically and recoiled very harsh(for an AR) and launched brass into the Stratosphere and really dinged it badly. I replaced the BC on the Bushy and the gas key on the mutt and both cycled fine afterwards.

All an AR needs is rearward motion imposed on the bolt carrier to unlock the bolt and overcome the buffer spring. On a gas impinged AR this is done by the gas impulse. On a piston AR this is done by the op rod shoving on the boss where the gas key used to be. I think on the 2 rifles aforementioned the gas impulse was enough to cycle them but seeing how none of the impulse was bled off through the vents on the bolt carrier that resulted in the hard recoil and launching the brass quite far for an AR. The brass was also severely damaged on both.

Interesting. Thanks for the update!