This project has become a source of unexpected problems.
I rented a floating collar reamer to ream this low wall 32 rimfire chamber to 32-20. I cut the new chamber very slowly and carefully, using plenty of Tap Magic and stopping often to clean out the chips. I cut all the way to the rim recess--at this point the chamber was very clean smooth. The reamer quit cutting at that point. It will not cut the rim recess. On very close examination it looks as if the flutes are ground with no cutting angle on the part that ought to cut the rim recess. I know that some 32-20 rifles, such as my Mod 1853 Browning, do not have a rim recess in the barrel, but of course the low wall must accept the rim in the barrel.
Are there different reamers for these different rifles? I do not see this in any of the web ads for reamers. Is there something else I am doing wrong? Any help greatly appreciated.