Sig Sauer SIG516 G3 Mohawk 16" 5.56

The SIG516 G3, sold as the Mohawk, is SIG's third-generation take on a piston-driven AR-15. Where a direct impingement rifle vents combustion gas back into the receiver, the 516 drives a short-stroke pushrod against the bolt carrier, so fouling and heat stay forward of the chamber. The gas valve is fully adjustable, which is the feature that matters most on this rifle: you can dial the port down for suppressed fire, open it up for a dirty gun or weak ammo, and shut it toward off entirely.

The G3 revision is where SIG addressed the ergonomic complaints leveled at earlier 516 generations. Controls are ambidextrous throughout, and a steel non-reciprocating side charging handle sits alongside the conventional rear handle, so you can clear a malfunction or press-check without breaking your firing grip. The free-float M-LOK handguard replaced the older quad rail, dropping weight and letting you place lights and lasers where you want them.

At 7.7 pounds it is heavier than a comparable direct impingement carbine, which is the standing tradeoff for any piston AR: you buy cleaner suppressed running and adjustability with weight and a more involved parts count. The 16-inch cold hammer forged barrel wears a 1/2x28 SIG flash hider-compensator on a tapered shoulder, and the rifle runs a standard AR-15 fire control group, so trigger upgrades are the ordinary aftermarket parts you already know.