A mount adapter device utilizing a spring-loaded push system for quickly and securely attaching accessories to weapon accessory rails is disclosed. The mount adapter device generally includes a first base member, a second base member, a push rod member, and a resilient member. The push rod member connects the first base member and the second base member. The first base member is linearly slidable into engagement with the second base member in a first direction, and the second base member is linearly slidable into engagement with the first base member in a second direction which is opposite the first direction. The first base member includes a first clamping member for engaging a first edge of the weapon accessory rail. The second base member includes a second clamping member for engaging a second edge of the rail. The resilient member provides a spring force and is arranged to force the first clamping member to move in the first direction into locking engagement with the first edge of the rail while simultaneously forcing the second clamping member to move in the second direction into locking engagement with the second edge of the rail.