Bren L4 Build Oddity? (New to Bren builds)

Hello all,
I'm new here and I'm starting on a Bren L4 build and have some questions that I couldn't find answers to while reading and searching through the forum. So here goes nothing....

The kit: a Bren L4a4 that started its life as a MkIII with a 1945 date stamped on the side. It now sits in 4 torch cut pieces on my work bench. I actually ordered a MkIII parts kit and received this L4 by mistake from the company I ordered from. It actually turned out to be not such a bad thing as I mostly shoot 7.62 nato in my rifles, so one less caliber to shop for I guess.

The worst cut is in the barrel sleeve section of the receiver. It's not THAT bad and I've seen kits with much worse cuts in much worse places. It's mostly cosmetic and will be built back with weld (which I've already started. I'll get to that in a bit). There's about 80% of the original barrel shoulder/face left so I have an actual location to go off of.

My first question is more of a curiosity because I've never seen this type of thing come up in any Bren build that I've read or watched online. As I was welding the front of the mag well/barrel face/shoulder section, I noticed that there was some sort of separation in the barrel sleeve of the receiver. It looks as though there is some sort of "ring" sleeve on the front ≈1/4" of the barrel sleeve of the receiver. I never noticed this while preparing the kit for reweld. But when I was building up weld in this area, I noticed separation and movement of the "ring". Looking at Bren parts diagrams, exploded views, and blueprints, I can't find a name for this part or even proof of its existence anywhere. Being fairly familiar with most weapon systems, the only conclusion I could come up with is that, because this is a L4 and is modified from a previously mkIII Bren, it had a partial sleeve inserted into the bore to possibly fit a different barrel profile or tolerance for the 7.62 nato barrels? Can anybody confirm this? I haven't read anything about this anywhere.

I will attempt to post pictures of what I am talking about.

Here are some pics of the area. Please excuse the not-so-great welding and quick machining. Its a work in progress and it is far from done. I work on it when I get time.

https://www.milsurps.com/showthread....highlight=shim
I thought this would help you, but it doesn't:
The shims go onto the barrel, the collet looking thing is a tool to keep the shim square as it was installed onto the barrel.

My L4 as cut , you can see an edge of the "socket"

https://www.milsurps.com/images/impo.../vYK2WLt-1.jpg

https://www.milsurps.com/images/impo.../ubQ09gH-1.jpg

---------- Post added at 05:01 PM ---------- Previous post was at 04:56 PM ----------

Some dimensions that might come in handy.
I laser scanned a MKIIK for the hole locations.

https://www.milsurps.com/images/impo.../U26As0Y-1.jpg

https://www.milsurps.com/images/impo.../s7rYdts-1.jpg


https://www.milsurps.com/images/impo.../g0GzAuO-1.jpg

https://www.milsurps.com/images/impo.../Ya9a2mk-1.jpg

Wow, thank you for those! Those will absolutely come in handy!

The torch cuts on your receiver are pretty nasty. They got that torch nice and HOT when they sliced through that. The cutter must have been having a bad day at work.

When you say "socket" is that an official term? Or is this a term you came up with?

Do you have any idea why that would be inserted in there? Headspacing maybe? Or maybe it was heat treated harder due to the nature if it's location?

Also, I couldn't find a part name for this or that it even existed on any bren blueprints or parts diagrams. Is this strictly a L4 modification?

I'm wondering if I will have to have that area re-bored and have to turn out a new piece if I can't find one for sale online. That'd be a major operation to have that area re-bored due to the length of the receiver, the fixtures required, and the instability of what a lathe chuck would have to grab on to. I don't have to tooling to do that on a mill. I don't think I'd want to do it on a mill either.

cal50, thanks for the great reply! It's much appreciated.

That all looks SO hard to sort out. So much slag to grind and edges to rebuild...I had a .50HMG once to rebuild but it was nowhere near that destroyed. I understand the desire to bring it back though...

My shooting bud already put his L4 back together and his had the socket / insert. I also am not sure what the proper name is but its an insert / socket ,lol.
I have never seen an L4 that was not cut REALLY hard. I plan on machining a copper insert for the barrel socket area and welding everything else up solid then re-machining it to the correct specs.

I ground off all the slag and slid the pieces together and its in my pile of stuff to do.

https://www.milsurps.com/images/impo.../TVil8XZ-1.jpg

https://www.milsurps.com/images/impo.../YIaMyfB-1.jpg

https://www.milsurps.com/images/impo.../sBNr3jO-1.jpg

---------- Post added at 06:48 AM ---------- Previous post was at 06:46 AM ----------

Quote:

---

Originally Posted by browningautorifle

That all looks SO hard to sort out. So much slag to grind and edges to rebuild...I had a .50HMG once to rebuild but it was nowhere near that destroyed. I understand the desire to bring it back though...

---

Someone really enjoyed torching mine by the looks of it.
Its not a quick or easy fix but rescuing any old war horse is a good thing.

Quote:

---

Originally Posted by cal50

I also am not sure what the proper name is

---

Normally an item such as this is called a "bush", like a bearing or something to reduce a diameter or provide a harder surface. I can't think that it would be called anything else but there is probably another word to go with it describing what sort of "bush" it is, i.e. it's location in the receiver.

Here are some pics of my kit before I started filing and grinding and making it look nice prior to lining up and welding. The cuts on mine aren't bad at all compared to some I've seen.

And yes, I realize that those are MKII barrels and .303 mags in a L4. It's what I had on hand. When I ordered the kit, I thought I was getting a MK3 so I ordered 2 barrels and a mag to go with the kit that I thought I was getting.

That area in front of the mag will need an awful lot of work. There’s a lot of close tolerance parts to fit in there.

I definitely understand this. I'm not on a time constraint with this project. So no rush.

Which sections will have tight tolerances? I can't imagine the outside walls will have functionally tight tolerances. I figured the face that the barrel butts up against will have a tight tolerance and that's why I'm leaving as much of the original intact as possible. All of the faces on the inside of the magwell are original and in good shape. They just need some slag cleaned off. As far as the grooves for the magwell dust cover go, I can machine those after I get the other work done. I'm not worried about that. The barrel bore in the receiver is still intact as well.

As you’ve said, the breeching face of the barrel and barrel nut, the detent for the top cover and the mating cross detent for the barrel nut. The L4 modification included a role pin inserted from above to form the seat for the barrel nut detent spring, with out this the detent won’t work. How’s the recess for the front lip of the magazine?

Sorry for the long delay getting back to this thread. I had a lot going on in my life. New job, new house, etc. Anyway, jumping back in head first into this build I picked up some necessary tools and parts I needed to get moving on this L4. This whole thread was about the ring/bushing/spacer object that was protruding slightly from the barrel socket. Well, after quite a bit of frustration and persuasion with some prying tools and a blacksmithing hammer. I removed the bushing from the barrel socket. This needed to be done as it was cocked and then welded at an angle due to building up weld on the top front area behind the barrel nut slot and not seeing it in the first place. Luckily, its a very simple bushing and machining a new one shouldn't be too hard. It seems to have originally been a .001" press fit into the machined area of the face of the receiver. Seeing as I have enough of the bushing left to get a measurements on it. I should be able to replicate it in a few minutes on a lathe. The difficult part now will be to machine out the counterbore that the bushing fits into. When I built up weld in the area directly above it, a piece of it was welded to the top side of the counterbore leaving some of it permanently welded in. I will either have to get creative with my mill, or very carefully remove the rest with a rotary tool. If only I could get my hands on a full set of blueprints for this thing. I've scavenged some pictures of old blueprints for Brens, but most of them are very hard to read.

Brit plumber, sorry for the delayed response to your question. The recess for the front lip of the magazine is untouched other than some weld slag that can be easily removed. I picked up a couple of (surprisingly expensive) L4 magazines that are in good shape. I should be able to use these the get me in the general ballpark of placement of the receiver pieces.

is this the info you are after ?Attachment 127490Attachment 127489

Item 2 in the drawing

This was laser scanned from one of my Bren cut receivers.
The dimensions minge be handy~


https://www.milsurps.com/images/impo.../g0GzAuO-1.jpg

https://www.milsurps.com/images/impo.../Ya9a2mk-1.jpg

https://www.milsurps.com/images/impo.../tIuSugv-1.jpg

https://www.milsurps.com/images/impo.../s7rYdts-1.jpg

https://www.milsurps.com/images/impo.../U26As0Y-1.jpg