If the barrels are in good shape and have good wall thickness, I'm comfortable with anything up to about 7000. This seems to be an oft-repeated figure among many shooters. I believe this is about what a standard vintage black powder load would generate.
All of my target loads actually are significantly lower than 7K, but some of my field loads are pretty close, or right there at it (turkey loads).
One day I was shooting Sporting Clays with my 2-frame DH damascus gun. I was shooting with a friend and we were using his golf cart. I didn't realize it, but he was shooting factory loads in an identical box and using the same hull as my low pressure target reloads. Somehow we got switched and I had shot nearly a full box of his factory loads (Federal promo 1-1/8 oz.) before I realized the mistake. The old DH didn't care one bit. Since promo loads are designed to work well in autoloaders, I'm sure they are over 8k at least. The friend whose shells I accidently pilfered was shooting them through a fairly light Francotte damascus gun, and has done so without a second thought for years. My gasp at realizing my mistake was a non-issue to him.
On another occasion, I had welded a pinhole in a 2-frame damascus GH barrel, about 7 inches from the breech. It appeared to be a factory defect as there was no corrosion anywhere near it. It was between the ribs and never would have showed up if I hadn't refinished the damascus pattern (found it by the leak into the bore). We stripped the ribs, welded the hole and re-laid the ribs (and refinished the barrels...again). I proof tested that gun with a few factory loads that Kent listed at 8100 psi. No problems, so I stuck a Winchester Super-X 3-3/4 dram, 1-1/4 oz. load in it and pulled the string on the trigger (gun tied to a tire and me behind a steel drum). Again, no problem. A bore mic showed no changes at all anywhere in the barrel. I don't know what the Super-X pressure was, but judging from the roar and recoil, I'd guess it had to be pretty high (although that's not proof that it is).
Jim
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