It occured to me that it would be a faster reload if you replaced the magazine before you fired your last shot and its hard to count your shots. Why not make it so your gun automaticly drops the mag when it is empty but one more bullet is in the barrel? The mag is useless by then anyway and if you have the time to put another mag in before you fire your last bullet that would be the best time to do so. If you choose not to put another mag in and fire the last shot then the slide should lock back.