The load was correctly loaded and I thought I caused this because the load was at higher pressure than most of the loads on the Hogdgon recommended load Chart, but below the never exceed load.
load info. is 125grn fmj .355 Hodgdon universal powder 4.3grns oal 1.090
I doubt if a correctly loaded cartridge to the above specs did the damage. I'm not sure if a double charge of Universal would fit in a 9mm case, but chances are there was too much powder, or maybe a 147 grainer snuck into your bullets.
As you mentioned, maybe there was something going on with the gun's assembly. How many rounds were through it prior to the incident?