Ah, yes, but on the NZbutt frames, they just overbored the hole in the butt frame and inserted and soft soldered a bush into that. Didn't touch the main casing. Heat the main casing unevenly and you wouldn't use the gun again anyway as it'd distort unevenly due to...... many things!
The bayonet standards would knock out very easily with just a mild blow in my experience but it'd leave the reinforcing plate behind. In Malaya/Singapore there was a local EMER instruction that if the bayonet boss was missing then we weren't to Y or ZF the gun as in that theatre or operations the lack of the bayonet fixing facility was of no consequence and the gun was considered serviceable.
But nice SMG's. The Rolls Royce of SMG's in my humble opinion