Hah... yeah it's a PITA here too.
I'll rework the headspacing deal.
Also, part of the reason why I don't have as much chance of that happening with this, is that I removed the super-tight plastic wad pieces, and halved the powder. There's considerably less force trying to escape the barrel than there would be with a normal cartridge.
I've got two barrels for this one... I'll probably use the short one.
I actually have two 12 guages, but the other one is 80 years old, all walnut and nickel steel
she's purdy though, so I don't shoot her.