Thanks for all the kind words.
I grabbed the Swamp Fox ammo and mag out of the trash, and dropped the ammo into the conversion barrel. I dropped about ten into the barrel, all went in just fine. Just to be sure that my thinking isn't skewed, I took some 10 mm ammo and dropped into the 10 mm barrel....the fit is the same.
By figuring out what it is not, we will hopefully figure out what it is.
And, just so we can say it has been said, the correct ammo(40 cal) was used in the correct fashion (used with the 10/40conversion barrel, which I have used in the past with no issues), and no I was not drinking alcohol prior to the kaboom.
I understand that the repairs are all on me, that Mike is no longer with us, and the gun was not stock.
I did have some work done on the grip, with a grip reduction. Don't know that it has anything to do with anything, just want to give the experts all the info I have at the moment.
I have had no issue shooting nuclear ammo 10 mm rounds(Swamp Fox and Underwood and Double Tap). I am completely clueless.