Bren L4 / .308 build

[cal50]

So it begins with a Sarco torched L4 parts set.
These were cut hard and will take some TLC to get it working again.

The bolt , carrier and gas cylinder & bipod are the only non-molested parts.




















---------- Post added at 06:19 PM ---------- Previous post was at 06:18 PM ----------

I have one of the barrels Sarco sold with the parts set that needs fitted and chambered.



---------- Post added at 06:20 PM ---------- Previous post was at 06:19 PM ----------

I have no lock nut area on the front.....
Going to use a piece from another build to replace.


The barrel socket and related holes are my 1st step.
Going to weld up solid and re-machine details.

I laser scanned a MKIII section for dimensions.
Much easier with real dimensions.











---------- Post added at 06:22 PM ---------- Previous post was at 06:20 PM ----------

Relaxing day to do some welding...







About time to start cutting the weld I added to the missing sections. Copper slug in barrel socket did its job and had good fill out. My receiver has a socket insert where the barrel is inserted. They torched about 1/3 of it away so I welded it up on the face to hold it then build up the other missing areas. I have a cheap IR thermometer and weld until the temps hit 450'ish then give it a break then weld some more.

Left part of the original dust cover detent hole visible and the new one I drill should line up and clean it up.















---------- Post added at 06:23 PM ---------- Previous post was at 06:22 PM ----------

Starting to machine welded areas. So far looking good with no voids , nice welds that are machining clean with carbide tooling.


One set up to match the angle on the mag well , inside area that was torched and the slots for the dust cover.
Next set up will be machining the barrel socket face and receiver sides.










Worked on leaves for a few hours today , A flame thrower would be more fun getting them while on the tree.........


After welding the torched barrel socket I needed to massage it a little to get it to accept a Bren barrel. Socket internal diameter in .903"

The copper slug I put in the cut section did its job and I had a very slight amount of material to remove. Rather than buying a flex hone I made a simple lapping tool from round stock.

I used some valve lapping compound turned by hand with a socket to lap it out.

I will hand stone the face and other welded areas , blend them & blast it and more forward to doing the barrel nut section when I can get a block of free time. Work sucks at the end of the year for me but at least the yard work is ending.

Fixing the barrel socket is a fair amount of work and what keeps a lot of cut up Bren's from ever firing again.
The rest of my build should be pretty conventional.









Next up was drilling the detent holes for the dust cover and barrel nut. Dust cover hole is parallel with the front barrel socket face. Barrel nut detent in on an angle. Everything machined nice without any surprises.









Moving on to the next section : Trashed barrel but area.

Torch guy wiped out the front barrel nut section as in its gone. I have a section from another parts set to use as a donor.
I will turn a copper slug the length of the barrel nut + an undecided amount to account for weld shrink.

Need to trim some pieces and fixture it up.


Blasted in the white~




Thank you torch guy~



---------- Post added at 06:24 PM ---------- Previous post was at 06:23 PM ----------

Barrel socket was about 3 sticks of filler rod and good practice for laying beads.

Next up -






Cleaned up the rest of my L4 , stripped all the parts and degreased everything including the wood. Discovered my bolt , slide , lower frame and what's left of my receiver all have the same serial numbers which was a big surprise. My other Brens are typically mixmasters. Internal parts are in really nice shape and not fired much from the appearance of parts, bolt face and gas piston. Wood has a good amount or wear around the sling attachment point. It was put away dirty and have some surface staining and has likely been that way for decades.







Tacked the barrel nut section together in six places , removed the oversize ( +.012" length ) copper spacer and clamp assy. I fabricated and will weld it up. Hopefully my fixture helps keep the barrel nut surfaces parallel.

Guessing the shrink factor is always fun.