A variation of what Mark E suggested: Load normally, and use a CO2 discharger to blow the load out and check for patch damage. Any cuts or tears would be attributable to mechanical cutting and not hot gasses.
Or, load and fire with about 75 gr by volume of corn meal between powder and patched ball and see what recovered patches look like. The cornmeal will act like a firewall and preserve the patching from the effects of the powder ignition.
I've got a Large barrel that eats patches. I tried multiple oil lubes and patch material, finally discovered that the patches survived with cornmeal filler, and also that one thickness of ticking with water/spit lube would work (but not the same ticking with oil). I suspect that 30 years or so ago a previous owner left the gun loaded and a rough area in the barrel developed back down near the breech, but it would take one of those fiber optic inspection scopes to prove it. Good luck with yours. SCL