I think you need to measure the neck length and the chamber face to the sholder, my guess is the chamber is short. For the neck to be short and the chamber the proper length to the sholder, the reamer used would have to have a short neck ground into it. Then there would be hundreds of these short neck chambers out there, plus the maker of the reamer would have had to make it short and then ship it to H&R and have H&R QC miss it. I just doubt you have what you think you have. Larry