It take about 5 minutes to switch back to your original setup to shoot the 45acp. I would go that route. 5 minutes more to switch back to the 460.
I do not know the XDm that well. In a 1911, there are some simple tricks to slow the slide velocity down and hold the round in battery longer. If your are getting 25' ejection, you are tearing your gun up. Simple as that. I would call Clark Custom.
How are your fired cases looking?
One more thing, quit shooting your chronograph. Ha! Ha!
