I was just thinking this , if the barrels didn’t blow out after 35 rounds it’s a well made barrel.
I almost don’t believe it, all squib loads I’ve ever seen blow the barrel all to hell, unless someone had some really bad handloads
A lot of 9mm carbine barrels are pretty stout and 9mm doesn't have the enormous pressure a rifle round does so it's not as likely to bulge the barrel.