Well, I got around to checking the barrel of my Desert Eagle, after having fired those 12 handloads. I discovered something rather alarming.
Scratches. Several of them, mostly close to the chamber with a few running a couple of inches down the bore. They weren't there before I had shot the loads.
I asked one other Deagle owner if he had had those kinds of problems. He reported none. He's shot 800 rounds through his without so much as a mar inside.
Huh. I wonder if it was the bullets I had loaded, or the cartridge overall length. Whatever the case, this particular barrel is going to be used only for handloads from now on, and I'm going to watch it closely.
Unfortunately, MRI doesn't manufacture any more Mk. VII barrels, but they did have several 10-inch barrels in stock. I was looking for the standard 6 inch. The guy I talked to in sales said they had a few demo barrels, with a couple hundred rounds through them, but scratched some on the outside, so I bought one of those for $250.
I will eventually have to get a conversion to the Mk. XIX, which entails a new barrel and slide, for about $750. Once I get the cash to spend for that, I'll do it.