Yikes-

Not really a lightweight there either.

If you still have those barrels, I'd really like to see good photos of the ripped metal. There's a story to tell in there. That metal's got things to say for sure.
Likely that anything that the missing parts would tell would also show on the broken reamains of your barrel.

The wall thickness would be (for the most part) able to be measured as well.

I was on the phone the other day with a contributing editor to one of the more respected magazines featuring this kind of gun. We were talking about damascus barrels and loading for bore rifles.
Blown barrels were a topic of conversation somewhere along the line there, I wanted to hear a real-ass first hand story of a blown barrel.
He couldn't come up with any account of a damascus barrel going haywire in the field, but was able to share with me a story of an american double he'd blown, right about where your rifle went -- ahead of the forend.

That gun had just gotten back from 'restoration'. It had been in the hands of a reputable artist too. The barrels had been struck down to (hold on boys and girls...) about eleven thousandths -.011"- of an inch there.
Whooo-golly that thing was asking for it.

I'm not suggesting that this was the case with your rifle, I don't know squat about what happened the other day with you and your friend, and all I know now about your rifle is what I found looking through your history of posts here on the site.
Your rifle looks attractive, looks like it's been completely restored at some recent time too.

I'd really be interested in seeing what the torn open surfaces of that barrel look like.
I have an english double from the early mid eighties that I'm about to start in on with regulation and load development, soon as next week. It's a ten pound .450 and seems rather sound. I won't be getting near the nitro load pressures you guys were likely working in, but this has me thinking of taking it to the lab for a good dye job, magna flux, and x-ray before I run it.

--Tinker