Bren semi auto build - USA

[garthok]

If you start to burn through the copper it will stick, you can try going with thicker copper or let it cool a bit between passes. I am alternating opposite sides and going slow to try and minimize warping and shrinkage. I had burn through issues when I was trying to use brass as a back plate on another project. With my aluminum jig I can wipe off the burn marks, it hasn't melted at all.

[Peter Laidler]

I have to say that I truly admire your perseverance Garthok. Can we see a couple of up to date-ish photos of your progress. Thanks. When you hear a Bren roar into life for the first time again, you'll appreciate just how worthwhile it was. A bit like restoring a 750cc Norton Commando motorcycle engine and hear it roar again. No tinny Japanese screamer there, believe me!

I remember one day after rebuilding mine (the Commando that is.....) I was stopped at a busy junction, waiting to pull out, when a bloke in the car next to me slowly wound his window down and said to me '..... just for old times sake, will you blip that throttle once again, just so that I can drive home a happy man' He got his wish........

[garthok]

Well, I have the lower semi mod complete, the upper rails welded, the blocking pin for the bolt on the right side, the left side cut is right where I am placing the pin and will be added after tack welding. I stopped here after I realized the middle two parts are slightly off, im going to have to cut it apart and redo at least there was progress...

[Joe H]

garthok,

I was looking through this forum searching for ZB39 Mags for the Bren and saw your post. Rebuilding the MGS demills into a working semi-auto is a challenging task. The IO demills are much easier.

I noticed you have not yet welded the cut through the barrel socket. Here are a couple of tips that will possibly save you a lot of grief.
When you have the cut jigged up and ready to weld put the barrel in place with the barrel nut and take the bolt without the extractor in place and slide it in the reciever. Put an empty case or go gage in the barrel and slide the bolt up aganist the case (or gage). With pressure on the bolt the case should be held snuggly in place. If it is not check the two lugs on the inside of the reciever they should allow the bolt to go fully aganist the case head. If they do not reset your jigging until they do. They appear to be there to prevent the bolt from battering the end of the barrel. If they interfere with the bolt travel you will never be able to headspace the gun correctly. Once you have this set correctly check to be sure the mag can be inserted and the mag catch works properly. If the spacing for the barrel socket weld is not right the mag may go in but the catch won't work. These issues arise only in the MGS demill because of the location of the demill cut through the barrel socket.
I've built two semi-auto brens (USA). The MK II was a MGS Demill.

Keep up the good work,

Joe

[Peter Laidler]

The internal parts in the body you mention Joe are in fact the breech block stops are are there to stop the breech block from touching the face of the barrel. HOWEVER, if you cannot get CHS because it is always too great, then it was permitted to carefully stone back the front beating face of the breeck block so that you could get CHS AND that it would clear the barrel face.

That's a great idea to align it all up with a breech block and a CHS gauge. After all, that is the ultimate true-to-life alignment set-up!

This only applied to the 7.62mm L4 guns but the theory and practice SHOULD also apply to the old .3093" guns

Keep up the good work Garthock

[garthok]

Thanks! that looks like the hardest part to complete. I got lucky on my kit, they missed the actual socket and cut just behind it.