I need a few questions answered. 1. what ranges it this gun good for? 2. Is their a aftermarket stock made for the 40 s&w carbine? 3. whats the life span of this gun. I have fired over 3000 rounds out of this gun and the 4 clips that i have arn't slideing up and and clicking in the whole way what might be wrong.? if any one can help thx?