Bought these for my revolvers, wife's semi auto's and rifles. They lock on all of them. DO they stop the gun from firing? Not on a single one of the 11 firearms we tried them on. As I said yes the locks lock. The issue is with the post. It does not fit behind the triggers it fits in front of them and wit enough slack that with minimal effort (our 5 year old grandson can fire the weapons) . Now before you go off on how unsafe it is for him to do so it was a test. Controlled and with empty guns we are not idiots. After all it is the kids that will pay the price for this lock not working.