Howdy
I think what Deeton is saying is that a properly tuned extractor will hold a case onto the breach face with enough force to allow the gun to fire. The 451 guns came from the factory with "heavy"hook on the extractor that could maybe hold the cartrige with a little more force to prevent an ACP case from slipping off the extractor and then allowing the primer to blow back into the breach face. If you try to chamber a ACP case in a $%!gun you will find that it appears to chamber properly but actually the extractor is headspaceing the case and not the case mouth. In any case DO NOT EVER ATTEMPT to fire anything other THAN WHAT THE MAKER INTENDED in ANY gun. I have an interesting collection of parts and pictures of people that have tried to proove that wrong.
L8r
Conley