CJF,
It seems that I had missed that you had fired the rifle with 22 Hornet ammo. I have a few samples of .297-230 ammo, and in my opinion you would not be able to chamber a Hornet cartridge in a "Morris" chamber. It might be possible to force a Hornet cartridge into a 22WCF/ 5.6x35R chamber. It would then be very difficult to extract the fired case( just as you described). A Martini can exert a fair amount of force to chamber a round; but hardly any to extract it. Based on this, I now believe your rifle is chambered for 22 WCF/5.6x35R. If you still have the fired Hornet case, if I'm right, it wouldn't show much difference from fireforming.
Mike
