Invented in 1946 by Chief Gunners Mate James E. Sieg of the US Coast Guard, the Sieg rifle was one of those rare American bullpup designs. Chambered in .30-06 and using a gas operated action, it could fire in semi automatic and fully automatic modes but lacked a selector switch. Instead the Sieg rifle featured a double trigger system. At fully automatic the rifle could fire at rates of 650-700 rounds per minute, and was fed from a 20 round detachable box magazine. Perhaps its most astounding feature was its muzzle compensator, which could be turned off to use as a flash supressor or grenade launcher. Most importantly the compensator was so efficient that it lightened the recoil to the point that a user could fire the weapon one handed. To make the rifle snag resistant the Sieg featured gentle curving lines and both the front sight and rear sight were foldable.
The Sieg performed well at Army Ordnance tests at Fort Benning, it is unknown why it was never adopted. The design faded into obscurity shortly afterwards.