ds, Yikes Glad your not bleeding!
Q's..How many rounds of 125's did you shoot before switching over. Did they all eject OK? Was it the 1st subsonic round after?
Did the barrel come out of the upper " easily " ?
Where did the load data come from?
Somebody mentioned on the other site that you didn't have a filler to take up case capacity. I'm not sure he understands the concept that the bullet IS the filler with this cartridge. I don't think you can get enough in there for an overcharge that dramatic, a stuck bullet makes more sense to me.