Bought it used. Looks like new. Shot 18 rounds through it, then it wouldn't set off the bullet. Took it to a gunsmith. He said the firing pin was working. He fired a new bullet through it...said I must have done something wrong. Got back to siteing it in today. It had been cleaned. I shot 18 rounds and then dead fire, twice. Got a shell from the box the gunsmith bought for me. It fired and also fired the two that hadn't fired before. ( You could see where the pin hit the primer on those two). After three shots, it missed again, twice. I put it away. Do you folks think the firing spring is weak? Or should I go a different route?