Just picked up an older 22 semi auto rifle and I can't get it to fire. I removed the stock and pulled out the trigger assembly and when I cock the hammer with my thumb, it will fire. Every time I replace the trigger assembly and put the rifle back together ... it's the same thing ... nothing. I've determined that when the bolt assembly is fully pulled rearward to chamber the first round, it's not fully cocking the hammer. I just don't know why. Anybody out there know what the cause might be? My best guess is that the bolt is just worn out or ground down slightly enough to not push the hammer completely down. But the bolt doesn't look worn and I'm just completely guessing. I am by no means a gun smith, but I like to tinker and was hoping this was something I could fix. Any help or advice would be greatly appreciated. Thanks.