Carbine gas system
Was asked the other day about the various gas system lengths on the AR platform. Specifically, which was best and why. For this particular discussion, we were talking about a 16" barreled system, to which I would recommend the mid-length over the standard carbine length gas system. My reason, in a nutshell, is that the longer mid-length system on a 16" barrel more closely resembles the barrel/dwell time ratio on the original 20" barrel that the system was designed for. In my own experience, the mid-length system has less felt recoil and does not seem to be as hard on the BCG. The carbine length systems with their longer dwell time, develop higher gas pressures resulting in a higher failure rate due to metal fatigue. When I was teaching full time, I would see a high number of fractured locking lugs, broken extractors and even some complete bolt bi-sections (at the cam hole) on the rifles with the shorter gas systems. This is not meant to say that all carbines with the shorter gas system are doomed to imminent failure; just between the two, the mid-length will serve you better....IMHO.