The Reising cost less than the Thompson because its metal components were mostly stampings instead of machined parts. This also allowed it to be lighter, as did its firing mechanism. Like the 1928A1 Thompson, its operating principle was delayed blowback, but the Thompson's Blish lock system was far less mechanically effective and so, like a simple blowback weapon, the Thompson was dependent on high bolt mass or more specifically bolt inertia to provide an acceptably low rate of fire. That is, a lighter bolt, as used in earlier models of the Thompson, would have reciprocated faster and produced too great a firing speed. This in turn meant that the Thompson could not be radically lightened without a deterioration in its controllability, as a heavy gun was necessary in automatic fire, to counteract and stabilize the effects on control and accuracy of its heavy bolt moving back and forwards. The Reising's bolt is much lighter due to its delayed blowback mechanism being the main determinant of the automatic rate of fire; and consequently the whole gun could be correspondingly light without detracting from accuracy and controllability.