Charlie
There should be no problem with the frame at all, shooting these singleshots such as the Encore and Contenders are a different experience when it comes to headspace,what happens is the loaded round is down in the barrel too much and when the fireing pin hits the primer actually backs out of the brass then the brass slams back against the breech face re-seating the primer and flattening it out making it appear to be overpressure but actually its normal pressure.

Albert