| Direct gas impingement AR-15s suck. Wait a minute, maybe that's piston driven AR-15s suck. Now that I have your attention I'll say they're both good and each has its own pluses and minuses that need your consideration. Long proven in many battles, the DI (direct impingement) M4/M16/AR-15 series are very reliable if maintained and lubricated properly. If it were not so it never would have lasted this long in US military service and many of the "it's broke, its needs replacing now" arguments ring hollow with me. That's not to say it cant have its problems and is failure-free. In the DI design by Eugene Stoner, the introduction of cyclic gas into the receiver makes things dirty and heats up critical components. That heat can accelerate wear and possible parts failure in extended full auto fire and makes cleaning a chore. Also running shorter barrel lengths on a DI gun is taxing to the system and it often needs heavier buffer, spring, and maybe even port adjustments to ensure reliability. Count on some tweaking. Also running a suppressor off a DI gun can cause debris and powder to be blown back into the users face, even with charging handles that incorporate deflection channels. The current piston AR-15s, like the Ruger SR-556 shown, promise to cure many of these problems. They transfer the heat and dirtiness up front at the regulator/piston mechanism, keeping the bolt cooler and cleaner. From my experience at this point, piston ARs will foul in the piston/regulator area and ... |
