Bren Locking nut handle interchange

[tr63]

What is the difference of the MkII and the Mk3 locking nut handle ? Can one be used in place of the other on MkII Bren Gun? I understand there are different sizes in locking nuts, what will a larger size change on the way a barrel fits the receiver ?

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[Peter Laidler]

LOCKING handle? What do you mean. Locking nut or cocking handle? But generally speaking, all parts were made so that they could be interchanged. If not individually then as assemblies.

[tr63]

Sorry Peter, locking nut is what I meant . If you a use a locking nut to replace a size 1 and replace it with one that is a size 2 what will this do as far as the fit of the barrel . ?

[Peter Laidler]

Well............. The fdirst thing is that like No4 bolt heads, SLR locking shoulders etc etc, a No2 barrel nut is not necessarily the next size UP - nor down - to a size 1. Looking at the number size is for the fairies.

What's the difference? It's all external basically. The Mk2 type is a simplified version while the Mk3 type is a lightened version of the Mk1 type. But to us on the shop floor, they were all the same and did the same job. All the barrel nut does is draws the barrel rearwards hard against the gun body, locks down and keeps the barrel tight. It really has no bearing on the CHS or anything else that I can think of.

[Flying10uk]

I understand there are different sizes in locking nuts, what will a larger size change on the way a barrel fits the receiver ?

Are you able to clarify what you are asking here, please? Where you under the impression that there were barrel nuts available, at one time, with normal, loose and tight threads as well as being in MK1, 2 & 3 form?

[tr63]

Yes , it was my understanding that there is are barrel nuts that varied in size and the way they fit which affects the lock up of the barrel . Loose barrels maybe corrected with a different barrel nut being fitted .There are vendors that have for sale barrel nuts that vary in size and have markings that indicate sizing , ie 1,2,3,4 etc. .

[Brit plumber]

You will have fun on civvy street trying to find a nut that fits just right. That is unless you have a box of them but I'd imagine the cost would be prohibitive. You could find one that is too tight and then adjust the rear face on a fine sheet of sand paper on a glass surface. Do that until the barrel nut closes up just right, it may take 5 minutes it may take 30 but it will work. It shouldn't effect CHS unless it has been set up with a loose nut which allowed the barrel to move forward.

[Peter Laidler]

But a respectful warning re BP's thread 7. Barrel nuts are diamond hard and adjusting the faces is a non starter unless you have a surface grinder in my opinion. They are made diamond hard just so they don't wear away at the rear surface. Doing that will also make the barrel nut loose in the opening. And the last thing you need are sloppy nuts!

As a matter of interest, learning about the mechanicals and theoreticals of the Bren during our apprenticeship took 3 months. That was after the we'd already learned the principles of heat and principles of small-arms. That is 3 months learning about the what's why's and wherefores of the Bren/L4's. And if you think that the interrelation of the No4 bolt, bolt heads and parts is difficult to get your head around sometimes, then the relationship between Bren barrels, CHS, locking shoulder, stops and barrel nuts is something else............

[CINDERS]

And the last thing you need are sloppy nuts!

Geez Peter here I waz thinkin that you always used the Queens English! Indeed Sir!!!!!

[Peter Laidler]

I do Cinders. Or at least I did until I learned the REAL Queens English in Australia. Never mince words I say! I also learned that even in the most serious lesson or class etc there's always time for a smile or a bit of humour. Same as the forum really.