dang that is a bummer, im not really sure im sure the other guys on here can answer this better than me, but boy, i dont think H&R would like to see a barrel that someone has tampered with especially when people arent really suppose to tamper with that stuff, they may not take care of your problem. But like i said im no expert but personally i dont think they will do anything about it. Sorry man, hopefully someone has some better news for you.
Please post what you find out
Thanks
adam