As I recall the G grade Parker which which was "Blown Up" at about 30K PSI was badly pitted throughout the bores. The pitting was apparently not what caused it to burst, but the pressure had simply exceeded its limit. It blew between the chamber & the hole for the extractor leg, as did a similar steel barreled one at near identical pressure.
Buck Hamlin also tested both an L C Smith & Lefever (forget the grades) with badly pitted bores. Both were rechambered for 3˝" shells. He began with the heaviest reload listed by Alliant using Blue Dot powder behind 2 oz of shot & went up from there. He stopped on the Smith when the gun would no longer stay bolted when shot, that rotary bolt became a "Self Opener".
He went even further with the Lefever (its simple wedge bolt in the Doll's Head stayed bolted) until he produced a bulge out where the walls had been thinned by the extended chamber. Realize of course this was a 3/4" chamber extension, not the usual Ľ" from a 2˝ to a 2 3/4" chamber.
Those old Damascus barrels are just not as weak as we have been told. Most of them which have burst over the years,, "When" a proper investigation was done has been revealed were burst for some other reason than that they were made of Damascus Steel. A lot of early mis-understanding of Smokeless Powders resulted in a good number of burst barrels. Twist & Damascus barrels were high on the list for the simple reason they were the barrels in common use at that point. When these same Overloads of smokeless (from using a bulk dipper with Dense powders) were used in steel barrels they also Blew Up. The most common cause was, & still is, Barrel Obstructions.
