Buy it stripped or built at Angstadt ArmsBuy at Rainier Arms We've teamed up with Angstadt Arms on the release of a pistol caliber version of The Jack. Glock magazine fed. Available as the AR-15 lower (compatible with any 9mm upper) or a matched receiver set configurable in 9mm, .40 S&W and .357 SIG. The receiver features last round bolt hold open as well. Available through Angstadt Arms!