The M2HB is coming along I finally got some time to work on it. I managed to get it sandblasted which was a chore considering it also is a deact. My buddies shop looks like the sahara now as it wouldnt fit in the box. But after all that work I found the wire brush on a high speed drill did the trick. I also used a sand paper flap wheel and got alot of the pitting out. I'll post some before and after pics in another thread when I get a moment.
Now as for the Bren here that had been violated, the flash hider is dated 43 so its not original to the gun. Also it also was butchered by the welder (using the term loosely) as the gas adjust was welded to the gun and it cut right through. Its not salvageable.
Your right the barrel is a 41 looks like everything else is 42, its hard to tell as it looked like the gun was cut in two after the barrel nut.
Peter looks like you are dead on, it looks to have been grooved and filled in to accomodate a new serial number?
HI RES
130811233_OtgITYrS_3.jpg photo - mrclark photos at pbase.com
Theres more pics here on my site if your interested
BREN MKIm Photo Gallery by mrclark at pbase.com