Adams Arms builds a kit to convert your AR-15 rifle from direct impingement (a.k.a., the “shit where you eat” system) to clean-running piston-driven bliss (schematic above). The company’s carbine length system runs $379, and they reckon there isn’t an AR made that doesn’t need to make the switch. To that end, Adams Arms has just raised $2.7m in funding from the investment bankers at Littlebanc Advisors. According to the resulting press release, “The capital raise will enable Adams Arms to support increased demand from its distributors, dealers and OEM partners, including Brownells, Midway and Smith & Wesson.” Both Adams and Littlebanc are both based Where the Sawgrass Meets the Sky, giving further impetus to those who call Florida the “Gunshine State.” Without sarcasm or irony I might add. [Make the jump for the rabbi's epistle to Eric on the advantages of a gas piston AR---which don't necessarily apply to a converted AR. h/t David]
”A piston AR has the advantage over a direct impingement AR in that the hot, dirty gas that gets bled from the barrel and fed into the receiver to cycle the action in a standard AR is replaced by a piston.
With a piston, none of the hot, dirty gas enters the receiver which keeps it cleaner and cooler which extents the life of component parts.
The drawback of piston ARs is that the piston hits the carrier above its line of travel which creates a angled, downward force on the carrier known as carrier tilt. Manufacturers mitigate the tilt by increasing the size of the end of the carrier to limit its movement, but the force and friction is still there.
The advantage of the SCAR [over a converted AR] is that it was designed as a piston gun the piston hits the carrier in the line of travel (eliminating any carrier tilt).”