Long time lurker so hope you don't mind me butting in on this thread as it looks to be rather unusual and interesting !
Thank you to the OP dauph197 for sharing the pictures,much appreciated ........ but at the same time I have a blinding headache from reading 30-06,7.92mm,7mmHV,.280,.30/7.62 calibre conversion trials reports for the last few days.Of course the trials reports are the only ones that I know of and this wouldn't include any guns the Canadians didn't submit for trial in the UK.Needless to say nothing with this serial number is listed or is described or pictured similar in photographs in reports.
Without a round being presented to the chamber or a magazine offered into the mag well to narrow down calibre options a few questions and observations.
Usually on shorter round such as in the modified Bren to take 7.62x39 with an AK magazine
a safety bent further back can be found
Is anything like this present in the MKIIM ?
Also as has been mentioned 'usually' in a shorter round not utilising an adapted 'parent' calibre magazine but a new made specific magazine an ejector block adaptor is needed to make up the size difference such as on the Canadian .280 conversion.
This feature doesn't seem to be present ?
Is the ejector or extractor marked 7.92 ?
Although the serial number 0-0562 is similar in format to 'sterile' Brens it is located differently and all other 'know' guns are in the 1-###x to 2-###x range ,nothing apart from lack of inspection and proof marks points to this.The retaining pin locating the piston/piston extention (if original to the gun) is in the wrong place and the fire selection on 'sterile' guns should read 20-0-1 not A-S-R
The serial number is another mystery in itself.
The question raised by L.E. is interesting regarding 7.92Kurtz as the only UK design work on this (AFAIK) was done soon after the war with an adaptable type gun design for a rifle/SMG utilising a roller locking bolt.The drawings give it the designation EM3 (but date wise is before the EM2 rifle) but ??? if any prototype/s were ever made.
Not sure if anything experimental was done in Canada with this round ?
The 7.92Kurtz round used on a Bren would also have probably had to use an ejector block though ?
Also mention by L.E. - "The "lightweight 7.62 Bren" (P277) shows rivets holding the mag well adaptors in for the redesigned mag and ejector. Pattern looks a little different, but it would be nice to see the whole side view and top and bottom views of the museum gun."
The 7.62 NATO XP113 Canadian converted guns (S/N's 5&6) and as L.E. says have a similar design to them but also utilise an ejector block which as mentioned isn't present on BREN MKIIM.
What do the numbers ? read on the mag catch ?
Is there any chance of taking another photo of the magazine well with the cover pushed further forward to see if the extra machining is for the internal insert or some other reason ?
Although Canadian 7.92mm production was well underway in 45 (as indicated on the reciever) the magazine well walls to the rear seem to be thinner .303 ones (unless these too have been machined ?) so maybe as gaff has said "MkII M was converted from 303 to 7.92x57mm...." and this was another way by means of a .303 conversion of getting a 7.92mm Bren instead of manufacturing one from new ?
Sorry for rambling on a bit

but would very much like to know more about this myself.
Hope this thread goes on long enough to find an answer.
All errors,typos and bad spelling are my own.
All the best Kevin
P.S. sorry Warren your hat went in the bin !
