Bren Mk II mgfr '42, unfired until 2013??

[tankhunter]

As Peter will tell you, at FTR or repair at a workshop parts were replaced without regard to manufacturer of the parts. They'd grab whatever part was next in the bin.

Correct!

When Small Arms went through for overhaul. They were generally don 50 at a time of the same type of Weapon. So, EVERYTHING was stripped down to the last pin, spring Etc. ONLY the vital matching numbered components on a Bren.
IE: Barrel, Barrel Nut (Barrel locking Lever to you!) Breech Block, Receiver & Butt slide would be kept together. As they were matched & serial numbered. Also, if it was an LMG 7.62mm Variant. The Piston extention was ALSO kept with these parts.
As it too, was serial numbered. Peter as mentioned in a previous Post. Serial numbering the Butt slide was superfluous really. As TBH, the only 'Fitting' of it, really involved. 'Does it slide onto the receiver without binding'?......

If it didn't (Unusual) it was generally a Burr, or warped/ bent slightly.

Even during the Out Inspection phase. It WAS at times, the case. That the Barrel was slightly loose, with it's Matched & serial numbered Barrel nut (Locking Lever) due to in service wear.
in which case, the normal procedure. was to select the next barrel nut size up. Check for Headspacing & easy barrel removal & replacement. If it was Ok, then it was ENGRAVED (They were TOO hard to stamp. Without ruining/ damaging number stamps!) with that particular weapons serial Number. Rephosphated again, Suncorite spary painted. Oiled & fitted to the Gun.

Racks & racks of LMG's /Brens were churned out during My Time at Command Workshops. & Peter will also attest. That was a weekly occurance there at Warminster!

When repainted, Oiled up & New/ Refurbished Wooden furniture fitted. a Bren/ LMG Really DID look magnificent!...............