I'd suggest first a close visual inspection- looking for obvious dents, heavy pitting, bulged muzzles- also look at the receiver face at the firing pin holes for signs of gas erosion and "blowback"- then, as Buck Hamlin advised me, remove extractor or ejector blade(s) and set screws, suspend by lug hook with a bungee cord (over a padded safety area, in case of a "drop" and tap the barrels with a wooden dowell, breech to muzzle to 'ring'- If all that checks out, and you can, have the barrels magnafluxed inspected (same way they check welded pipe joints) and make sure the chambers are sized for your loads. I have a 1896 mfg. LeFever sideplated 12 bore G grade 30" Damascus barrels with 2.75" chambers and Mod/Full chokles that passed all those tests, and I shoot one ounce Lite target loads in it all day long-each gun is different, and there are many variations in Damascus and wear over the years- so your cautious approach is wise indeed.
