ThomasB,
I would give them a call. The F12 barrel should be 24" full choke 3.5 chamber. If you got anything other than that barrel, then they screwed up. I am not familiar with how the shipping costs are handled in a warranty situation, but it sure seems reasonable that you should be re-imbursed for your shipping costs to send it back to the factory.
To my knowledge, they have not made any 12 Tamer models. Not recent years anyway. Sure sounds like they dropped the ball. I would give them a call and they should be able to straight it all out.
cookiemann
I see that you have a range report posted before you posted here. Do you like the barrel you got from H&R?? If so, maybe just call them and let them know about the different barrel and see if they will reimburse for the shipping costs and just keep the barrel.