also... there were a lot of the gun brands made back then, some of better quality than others... also guns of this era ( even the better brands ) had large tolerance spans both over & under in what was acceptable... so consequently some had tighter than they should have been, barrels & throats, some of these guns were unsafe to shoot ( even with black powder ), when new... also as these guns got older, ( & used ) if they weren't cleaned right away, or correctly, the chambers & or barrels ended up pitted from corrosive ammo, thinning chamber walls, & increasing resistance of bullets going down the barrel... so the lawyers jump in, because "Joe Average" pulls out grandpa's old shot loose & ill cared for Colt 45, with chambers worn & barrel pitted, loads up a hard cast bullet at maximum "safe" pressures in the manual, & cracks a cylinder... he's not happy about wrecking a "priceless" family heirloom
I always slug the chamber, throats, & barrel, inspect timing, inspect for excessive pitting in the chamber or barrel, but even if there is pitting noted, if the rest of the gun functions, I have loads safe to shoot in them ( yes, using Trailboss ) & if need be, a soft lead round ball... on some guns, these may be shot at BB gun velocities, but Trailboss by design, works with as little as 0.5 grains in the smaller cases like 32 S&W... you'll note that most powders in the load manuals don't recommend going lower than a certain charge... I've found Trailboss safe with what I call "revolver check out loads" with only a pinch of powder & a soft lead round ball seated
BTW... I have a collection of 40 or so antique guns, that must be shootable to stay at my house... some guns like my old bottom break S&W in 32 RimFire, have yet to be fired, but it does function ( if it were a center fire, & thus reloadable, I'd be shooting it, but as a rim fire, I've not tried pulling bullets & replacing the black powder charges, or cutting the nose off the bullet, to lighten the projectile weight... MRS. MAG really likes shooting the better quality 32 S&W's no noise or recoil, & a bit of history