Abstract: A firearm optical sight adapter is disclosed. The optical sight adapter can include an adapter plate with first and second opposing mounting surfaces, and a registration pin extending orthogonally from the first mounting surface. The optical sight adapter may further include a socket having a recess extending from the second mounting surface to a bottom wall intermediate between the first and mounting surfaces and an aperture extending from the bottom wall of the recess through the first mounting surface along a first longitudinal axis. A removable mounting post can be configured to engage in the socket. The optical sight adapter may include a recoil buffer extending upright from the first surface.

Abstract: A firearm optical sight adapter is disclosed. The optical sight adapter can include an adapter plate with first and second opposing mounting surfaces, and a registration pin extending orthogonally from the first mounting surface. The optical sight adapter may further include a socket having a recess extending from the second mounting surface to a bottom wall intermediate between the first and mounting surfaces and an aperture extending from the bottom wall of the recess through the first mounting surface along a first longitudinal axis. A removable mounting post can be configured to engage in the socket. The optical sight adapter may include a recoil buffer extending upright from the first surface.

Abstract: A firearm optical sight adapter is disclosed. The optical sight adapter can include an adapter plate with first and second opposing mounting surfaces, and a registration pin integral with the mounting plate and extending orthogonally from the first mounting surface. The optical sight adapter may further include a socket having a recess extending from the second mounting surface to a bottom wall intermediate between the first and mounting surfaces and an aperture extending from the bottom wall of the recess through the first mounting surface along a first longitudinal axis, and wherein a periphery of the recess is not circularly symmetric relative to the first longitudinal axis. The optical sight adapter may still further include a recoil buffer extending upright from the first surface a distance at least 0.3 times a length of the adapter plate, the recoil buffer defining an opening therethrough.