7.62mm barrels

BREN BARRELS.........

This is a short article, really written by me based on nothing more than my thoughts and admittedly never having done it. But as you’re well aware, being an old school Armourer and engineer I’m a big believer in and having brought up in the era of ‘......where there’s a will, there a way’ Or in my speak, there’s a SIMPLE way. That said, I expect and hope to see some alternatives to what I’m suggesting. Thanks to Joe, Vince, Tom H, Tiriaq and others too.

What the US Bren builders are short of isn’t Bren barrels per-se because the place is awash with new and used/shot-out/clapped out or otherwise knackered .303” Bren barrels...... but more to the point, Mk2 barrels. The rub is that it’s not Mk2 .303” barrels you want, it’s 7.62mm L4 type barrels you want. What is lacking is the will - and where there’s a will, there MUST be an easy way. Ignore Mk1 barrels from this point forwards

We know from earlier correspondence that 7.62mm rifled tube is available from most of the barrel makers. We also realise that making 7.62 Bren barrels from scratch is......look chaps, unless you are millionaires with guaranteed sales in the thousands, forget it and get onto the real world we all inhabit. With all that intricate machining and equally intricate, accurate and delicate inter-related indexing of the many this that and the others - it ain’t going to happen at a realistic price, believe me. But what could simply happen is this. Sat with a barrel across my lap yesterday evening, I think that there are 13 indexable or inter related accurately machined features on a barrel, all of which render others or all hopeless unless they're dead accurate. I mean, what's the point of a canted foresight or a misaligned positioning slot?

Let’s take a bog standard shot-out or otherwise knackered Mk2 Bren barrel. The 4x principle diameters are this.
BREECH that intrudes into the main body: .906” dia for a length of .9” or so
LOCKING THREADS: 1.25” dia for a total length of 2”
UP TO CARRY HANDLE: 1.175” dia for a length of some 3.75”
CARRY HANDLE TO GAS BLOCK: 1.1” dia for a length of some 6”
GAS BLOCK TO MUZZLE: .88” dia for a length of 6” or so.

It is these diameters that should concern us but more to the point, the initial .906” dia and the final .88” diameters

Strip the barrel only leaving the gas block in place. (But to be honest, if you have a good capable press, you could even remove this too. It’s up to you. I would leave it. After all, it ain’t broke, so don’t disturb it!)

THIS is what you do and you don’t need to be careful how you do it either. You bore your existing 303” Mk2 barrel out from end to end to .7”. The drill that you’re using will naturally follow the path of the existing .300” dia pilot hole. From this you will see that EXTERNALLY the barrel remains EXACTLY as it was. And luckily for you every one of those mega important datums, accurate machining and inter-related indexing features are still intact. Simply by saving those important external features, you’ve saved yourself hundreds of $$$$$’s in future time and effort. So far, so good.......

Now you machine out the breech end to a diameter of .920” for a depth of 4” or so. But this time you’ll notice that you have machined away the complete breech section that seats into the main body of the gun. But don’t worry......., more about this later!

Your machinist with advice from a metallurgist should now machine down your 7.62mm rifled barrel blank so that the blank is .920” at the rear end, extending for 4” plus a bit and .700” for the remainder of its length. What we want to do now is take advice from a metallurgist as to the expansion of the barrel in a furnace into which the liner will drop. After it if in place the contracting outer barrel will grip the new liner absolutely. If done correctly, there is not even the remotest chance that the liner will ever move because hereafter, the liner will expand slightly faster than the and........... Anyway, take my word for it lads, the liner will remain totally and absolutely locked in place by the super strength of the radial grip over the barrel length. How do I know this....... Simple, that’s what they did with the satellite liner in the GPMG chamber*!
*they failed but for another reason.....

What you have to do now is to machine the new protruding breech end for diameter and length to suit your gun body. At the muzzle end you follow the tongue recesses for the flash eliminator rearwards and accurately mark them out for the flash eliminator that will be moved slightly rearwards to suit its new 7.,62mm barrel (length from gas block to end of barrel EXCLUDING f/elim = 5.5”). Ream the chamber to suit your CHS, crown muzzle, slide on flash eliminator and using existing hole in gas block, carefully drill out gas port.

There....., it REALLY is as simple as that. Some have suggested that a breech end dia of .9” is insufficiently safe for a full power 7.62mm cartridge. I say bollxxxs..... That’s how they already are and additionally, the barrels are already UK Military proofed as stand-alone. That is, proofed NOT fitted into the protective ring of a gun body. So if it’s good enough for UK Military proof, then it’s good enough for us. Likewise, some say that the walls of the new liner will be too thin. Once again, what a load of fuzzy-logic bolloxxs. The whole length of the liner is tightly surrounded by the strong full diameter of the existing barrel. And to illustrate the point, look at the diameter of the last 8” or so of an L1A1 barrel. Point taken?

Like I say, where there’s a will, there’s a way. And hopefully I have proved here that from a simple engineering point, there is a simple way. So let’s not hear any more waffle and crap about there being a shortage of 7.62mm Bren barrels. What there appears to be is a shortage of will.

Please feel free to come back with any constructive criticism and make this a lively debate

Peter,

I guess I'll throw in my 2 cents. Just as you said, if you were making a lot of these barrels and were doing them on CNC equipment I doubt the machining would be a big problem. Of course all the work would be setting up the first one :D.

I have a small home workshop. It includes an ancient Jackson vertical mill, it has a WW II war dept. tag on it, and a circa 1962 13" x 36" Clausing Colchester lathe. My comments are based on using this equipment and the usual variety of manual indexing equip and tooling. I don’t have the ability to drill/bore the hole required or to heat the parts for full sleeving. Even with heating I think you may need a press to install the barrel sleeve. Screwed up sweat fitting is unforgiving.

I'm not disagreeing that it could be done the way you explained, It's just that I would not choose to do it that with the equip I have available. I'd expect it to take a good bit of setup and trials to get the tolerances required for your method.

I’d start out the same way with a MKII or MKI barrel and a 7.62 barrel blank. The barrel round blanks, not contoured, I have seen are available 1.2 -1.25" in dia. I would use the largest available say 1.25". 10 -12" twist.
I’d cut the rear 5” off the bren barrel, bore it to .903. Cut it to 2.15” +. Note that the .90” unthreaded section of the original barrel will now have disappeared. Machine the end of the blank interference to .9033” (my best guess for a sweat fit in the bren barrel section). Make sure the machined section will protrude at least 1” past the threaded bren barrel section. You will machine it to exact length later. Heat the Bren barrel section and press it on the barrel blank. When it cools it will be on permanently.
Now going forward the next machined section is the boss of the barrel handle. The OD will be a little over the OD of the barrel blank so you will have to sweat on a tube to increase the OD for machining the handle boss. The holes have to be indexed for the handle but it is nothing critical since they set the location of the handle in the stops. With the threads now in place on the blank it is not difficult to index the barrel for further machining. Machine the handle boss.
The next item forward is the slot for the barrel indexing to the body. It is interesting to note that many WWII barrels don’t have this slot nor do the 7.62 SA barrels. Just some turning and milling.
Next is the seat for the gas block. Simple turning but it must be carefully fitted for press fit with the gas block you are going to use. Drill & ream for the gas hole and securing pin. Turning and milling 2 slots for the flash eliminator. Finish barrel contouring, machine the rear end and chamber.
It will be a lot of work and expense but I believe it can be done.
Here is my estimate of parts and additional tooling:
Bren barrel $ 85
Barrel blank $ 80
Chamber reamer $ 110
Range rod (reamer alignment) $55
Misc Bits, reamers, etc. $100
Total Material $ 430

The gunsmith I have used to re-chamber and re-bore a Bren barrel to 8mm mauser will not reline barrels for hi -pressure cartridges. Why I don't know why and haven't inquired. Other than 22 rimfire he lists a charge of $375 and up plus $100 for a new chamber. I doubt this includes sweat fitting a new barrel liner, probably just gluing or soldering a liner in a drilled hole.

Joe

Thinking out aloud Joe, as I'm prone to do lately I'm thinking of using up old shot out, rusty or otherwise unserviceable barrels in this respect. So the value would be pretty well zilch. In much the same way that we'd use similar barrels for BFA. Start by cutting away the rear .906" breech end dia but you MUST protect the barrel to body surface.

A lathe with a long bed and a fixed roller head steady could support a barrel mounted muzzle end in the headstock chuck while a suitably and easily modified .5" dia and then a .7" dia drill bit could be drilled through in stages from a chuck mounted in the tailstock. Easily achieved as the .3" pilot is already there.

Likewise, bore into the breech end .9" and then .920. That is the 'old' barrel part finished. Time taken using friends large lathe 45 mts. Time to clean up swarf, cutting fluid and lathe, 1hr! But no doubt there WILL be a machine shop locally that could easily do this on a cash basis. After all, this is simply deep bore drilling a hole as opposed to deep bore fine finish boring

Regarding the locating slot on the underside of the barrel. It's true that some Canadian (or was it UK) barrels didn't have this slot. But that's because the barrel was located between the large upright ears of the Mk2 gun blast deflector. That's why they are there. It would be simple to machine off the female slot part if it wasn't needed. But don't forget that once the external parts of the barrel are machined then it's got to be stripped down for bead blasting and phosphating (and painting)

Joe, Whats the spindle bore on your lathe ? if you can get a bren barrel in and fit a spider chuck or similar on the end of the spindle then you can drill /bore the original barrel, you need to make up a drill with extension, to get an idea on tolerances and heat required try a small example.

If you can freeze the liner too it helps....

Cant say I've done a Bren barrel , but relined a few .303 Enfield barrels to .22, very similar to Peters advice. the last one I did I used an unfrozen liner instead of the one that had been in deep freeze over night, all going well until the last 1/2" had to revert to the hammer managed to get it in but just..... I left plenty of meat on the chamber end just in case.

The outer barrel only has to nip the inner sleeve to radially clamp it. Because it's the total area of the clamping action plus the radial compression that does the job. Having said that, there will be other methods of inserting the liner. What about modern lok-tite compounds?

it would be easier to turn the blank to the required profile and then populate it with the profiled parts salvaged from a donor barrel.

bigduke et al,

My lathe has a thru hole of 1-7/16". Easily big enough for a Bren barrel without the fittings.

I'm not at all saying that what Peter suggested can't be done. If I were a gunsmith specializing in barrel work I'm sure I would be set up to drill & reline barrels.

I just don't have the experience to drill/ream to the tolerance required for a shrink fit. My experience with shrink fits has not been the greatest typical of that last 1/2"on your .22 cal reline. If it doesn't go in all the way you are screwed. 21-22" is a long way to drop in the liner before it seizes by being heated up by the outer barrel. And you need the furnace capable of heating a 24" barrel uniformly. Maybe dry ice for the liner. In any case unless you are experienced I doubt you will get it on the first try.

If the .9" in the rear and .7" insert is capable of handling the pressure on its own then the shrink fit wouldn't be needed structurally. Drill till the liner fits in maybe .001" clear. Even at a theoretical .001" oversize hole you would probably have to drive or press it in for that length (my best guess). Then hi temp solder at the ends and /or pins. Loctite will work but all retaining compounds/ glues will release at about 500 deg F. Typical gunsmith solder is 475, Hi temp silver solder is 1200 deg F and there are 750 deg F solders available Of course we are not building a machine gun barrel:D. Just thinking out loud for discussion.

I've never seen any shot out barrels for sale here. They may exist but the cheapest advertised is about $70 usually with a missing handle.

Mr E. I also considered that by sweating or soldering them on the barrel blank. I'm really not sure if it is less work that milling new ones. just another possibility.

You were right Peter, this will spark some interesting discussion.

Joe

AFAIK, the only barrełs with out the slot are the Monotype MK2 barrels. Lithgow and Inglis Mk2 barrels had the slot.

Joe
drill and pin like the SKS or AK
there is enough meat there to get 4 pins in the chamber end. all the other parts only need 2.
you could pin them and them weld over the pin then finish the area to hide it.
I have used solder paste in the past to do .22 relines and it makes the job easier. I have also used green locktite to do .22 liners and thats the easiers of all but I do not think it will hold up to the heat and hammering of a semi auto centerfire

well that more than 2c worth but its good value

I think that it's being totally unrealistic to suggest that starting a total external re-profiling exercise from scratch using a large outside diameter rifled barrel blank would be easier (thread 6) It's totally unnecessary because you already have it - on the old barrel! What's more, it's all accurately done at the factory using the original drawings and passed by the MoS examiners. All you gotta do is to reline it!

Shot out/worn out/rusty barrels appear to be unavailable simply because by definition nobody in their right mind would a) want to buy one and b) as a result, feel the need to advertise any for sale! That's just my logical pragmatic view.#

Here's another point to ponder too. As soon as you pin a barrel with a transverse cross-pin, the barrel is weakened at that point and is only as strong as THAT diameter. (not a STRICTLY mechanically correct fact as there are certain tensile and stress related variables. But it IS weakened!)

Obviously some of the operations such as drilling out the barrel length would need to be done commercially and that would be relatively cheap. Look chaps...... the gun trade in the UK were boring out No1 and 4 rifle barrels AND BREN GUN barrels into shotguns by the thousands...... And that was with the bodies attached! What's the difficulty in boring out to.7" over .410"? Drilling a Bren barrel is simplicity itself. But this time you ain't paying for a desk bound geek to draw up the radial and lateral profile on his CAD!
Nope, I'm of the 'can do' era of graduates/engineers/Armourers as opposed to the 'its too difficult' generation. They never thought like that when they were making the Bren to start with.....

There are guys in the North South Skirmish Association who lengthen and line barrels all the time. One is Robert Hoyt, but I'm not sure if he still does it. He cuts the barrel if it's not full length, then inserts a shouldered liner of the proper length(42"for a M1842). He secures it with epoxy. I've not heard of one moving.

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Originally Posted by Peter Laidler

I think that it's being totally unrealistic to suggest that starting a total external re-profiling exercise from scratch using a large outside diameter rifled barrel blank would be easier (thread 6) It's totally unnecessary because you already have it - on the old barrel! What's more, it's all accurately done at the factory using the original drawings and passed by the MoS examiners. All you gotta do is to reline it!

Shot out/worn out/rusty barrels appear to be unavailable simply because by definition nobody in their right mind would a) want to buy one and b) as a result, feel the need to advertise any for sale! That's just my logical pragmatic view.#

Here's another point to ponder too. As soon as you pin a barrel with a transverse cross-pin, the barrel is weakened at that point and is only as strong as THAT diameter. (not a STRICTLY mechanically correct fact as there are certain tensile and stress related variables. But it IS weakened!)

Obviously some of the operations such as drilling out the barrel length would need to be done commercially and that would be relatively cheap. Look chaps...... the gun trade in the UK were boring out No1 and 4 rifle barrels AND BREN GUN barrels into shotguns by the thousands...... And that was with the bodies attached! What's the difficulty in boring out to.7" over .410"? Drilling a Bren barrel is simplicity itself. But this time you ain't paying for a desk bound geek to draw up the radial and lateral profile on his CAD!
Nope, I'm of the 'can do' era of graduates/engineers/Armourers as opposed to the 'its too difficult' generation. They never thought like that when they were making the Bren to start with.....

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so you get a 303 Mk2 barrel and bore it out and insert the liner then when you profile the outside of the barrel to L4 profile then the parts on the original barrel become separated when the metal joining them together is removed. so in essence you end up with the same thing but by a different method except your parts are free to wander

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Originally Posted by gsimmons

There are guys in the North South Skirmish Association who lengthen and line barrels all the time. One is Robert Hoyt, but I'm not sure if he still does it. He cuts the barrel if it's not full length, then inserts a shouldered liner of the proper length(42"for a M1842). He secures it with epoxy. I've not heard of one moving.

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ever done a mag dump from a BREN 3 mags rapid fire, epoxy will let go before the second mag is empty

Nope....... When you re-profile a Mk2 barrel to L4A2 and 4 spec there's no need to remove/separate anything*. It is simply a matter of turning two completely round diameters (between the carry handle and the gas block) down slightly but ONLY IF YOU NEED ABSOLUTE AUTHENTICITY. *You remove the f/elim and bring it rearwards simply because you've got to replace the conical .303 one with a fluted L4 version in any case. In fact, best leave the conical f/e in place initially as it's a suitable large diameter receptacle for the rotating tail-stock spindle.
How do I know this? Experience! 3 months ago I externally turned down 18 Mk2's to L4A2 spec on a small Myford lathe. These 'false' barrels were to be used in dewat L4 guns so as to preserve the original L4 barrels. Worked a treat - if anyone would like to see an example!

Mechanically of course, you only need a zillionth of an " cearance to create a sliding fit between the outer 'barrel' and the inner liner. I wonder if the metallurgist JMoore and PBreaky would care to comment on the shrink-to-grip idea

Let's not forget that the external outlines of the 'new' barrels is cosmetic. and reducing the length of a .303 to the 7.62mm length won't affect the exterior service condition as would machining down for exactness

This is the best deal on a barrel blank I’ve been able to find so far. What do you think?

7.62x51-BLANK 7.62x51 Raw Blank 25" x 1.25" - Green Mountain Rifle Barrel Co.

They also have a 416 stainless for $10 more.

I bet this little outfit could/would turn it to the diameters you wanted if you were ordering 25.

Vincent,

That's the blank I would use. I've bought Thompson barrels from them before and the were true Mil spec AA++.

Peter,

Here is an interesting post I found from 2009. Based on inflation his current cost would be about $350. Doesn't say how he attaches the barrel.

Feb, 2009
QUOTE
"Its really not safe to reline a high pressure cartridge barrel."
Not so, Grasshopper. Please be careful about dispensing advice without the facts. We reline high pressure cartridge barrels in our shop all the time. The liner is larger in diameter than a 22 liner (about as large in diameter as a #1 profile barrel) with an enlarged portion in the chamber area, the barrel is reamed and the liner is inserted, then the barrel is chambered and crowned. What you end up with looks just like the original barrel and is completely safe to fire. Many times it will actually shoot better than the original barrel because of the closer tolerances of the barrel liner vs a 50-year-old barrel. You cannot tell the barrel has been lined after the work is done.

As far as the cost compared to rebarreling, the comparison is only as good as the price of whatever barrel blank you would use. Relining a barrel will typically cost about $300, rebarreling with a cheap barrel like a Adams & Bennett would be about the same price (because of threading the barrel and cutting the breech recess), but many barrel blanks will actually cost as much or more just by themselves than the whole relining job. Before you decide which you want or need, decide what you want as a result, then find out about prices. You can PM me if you are interested in relining your barrel. QUOTE

I think I'll try to contact him.

Joe

This may sound daft but perhaps if there was a few interested parties, You could do a group buy/ resleeve, maybe even one of the companies like SARCO or IMA would get in on the act. If it was legal over here I'd get involved.

Brit,

Sarco has advertised that they will supply new made barrels for those who bought or will buy their L4 kits. I don't know how many kits they imported but its probably a good production run for a barrel maker. To date the barrels are not yet available. No availability date is promised. If you want their kit this would be the way to go assuming they come up with the barrels.

All,

I emailed to the supplier mentioned above in detail what I would want for a .308 barrel reline. i included a pic of a MkII barrel. All I asked about was the reline, no finish contours, fit up to receiver, short chamber, just install the reline. Told him it was for a semi.

Unless somebody is familiar with the Bren you would have explain in detail with a drawing to show what you want.

Here is the response:

"The liners are made from 4130 steel which is a bit softer than 4140. I don’t recommend it for 308. A new barrel could be made form a 30 caliber blank which would hold up as well as the original. The only problem would be fitting it to the action, I can’t have an automatic in the shop."

I won't pursue a reline any further. If I want the L4 barrel I know how to make one.
Joe

That sounds like a good marketing ploy Joe, or as we say here '.....hook the buyer first...' Sell them a flame-cut body and kit with the promise of a new made 7.62mm barrel '.......later'. No availability or price announced, only '....later'.

A reasonably well equipped shop can deep drill and re-line a barrel. If they accurately reline by contraction old car and aircraft engines it would indicate to me that they're doing something right. I suspect that the stumbling block is the distinct lack of interest due to quantity. Added to the promise of '.......later'

I look on relining an old barrel to suit in much the same way as we reuse old barrels as DP or Blank firers or re-using/converting a No4 butt to suit your needy Mk5 Sten gun. Waste not, want not - in terms of time, effort and materials. After all, someone else has already done half the work for you!

Peter,

Here we call it "Bait & Switch". I think the reality is that most of the barrel guys are thinking about sporting firearms, not sure even with the pic he understood the amount of machining required on that barrel. Just as you say there is somebody out there that will do it, but finding them especially for a one off project may be nigh impossible.

Joe

Yep, couldn't agree more Joe. It's finding the right people that will do the job AT THE RIGHT PRICE. It's like I find having No32 telescope parts manufactured. in v-small quantities. But I find some of the small home model engineers are superb. There will be someone with a larger home engineering hobby shop that can do.

I heard from a uk bit-part forumer yesterday that the UK gun trade have an outsource worker who deep drills their old No1,4 and Bren barrels (when they used to do this sort of work several years ago, The special drill bits were attached to a 24" long long high tensile steel rod and worked through the rotating barrel, fed with oil, from the tailstock end by hand pressure. Prevented from turning by a wooden tommy bar handle attached to the end. A standard drill finish was obtained of course.

But if the barrel was to be relined, it was left like this. If to be become a shotgun size (a technicality for certain UK laws at the time.....) it'd be honed by hand in a similar manner. Clever eh!

I wish some more forumers would come on board with ideas, plusses and minuses, pro's and cons because together we WILL make advances, believe me. Many minds make light work and all that

From a UK point of view, if we can have L1A1s as straight pulls, we surely could have a Straight pull Bren with a lined barrel or new made barrel with no gas vent. That would be another small potential market. Obviously there would need to be other modifications to gas parts etc. But it's another possibility.

Straight pull Brens......... In the UK............ Legally owned and used........ I think someone needs a word in your shell-like BP!

That sounds like an interesting proposition. If we had a print and an order for 50+ barrels then it might be something we could tackle. An order of a couple hundred and we could probably manufacture them at a much lower price point. Tooling up for production would probably be the trickiest part.

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Originally Posted by Brit plumber

From a UK point of view, if we can have L1A1s as straight pulls, we surely could have a Straight pull Bren with a lined barrel or new made barrel with no gas vent. That would be another small potential market. Obviously there would need to be other modifications to gas parts etc. But it's another possibility.

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Strange you mention it BP, one lad at my local club mentioned it last week...... After one lad had bought a Deac Bren.

With the EU directive around the corner, I'm wating to see what they will do regarding our semi Auto .22's plus other things on the hit list, lets hope common sense prevails, but as its EU I doubt it very much......

EU, MP,s & Common sense!!!! Those Word's don't function together Mate! LOL. When have you EVER Known a Government Department.
Actually Function on Common Sense?........:madsmile:

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Originally Posted by Peter Laidler

Straight pull Brens......... In the UK............ Legally owned and used........ I think someone needs a word in your shell-like BP!

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Just a thought Peter, I never would have thought an L1A1 would have been UK legal either but there are maybe double figure quantities being used regularly now.

Josh Beuge, Criterion. PM sent. Peter

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Originally Posted by Brit plumber

Just a thought Peter, I never would have thought an L1A1 would have been UK legal either but there are maybe double figure quantities being used regularly now.

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in regards to UK laws what would be the status of a newly designed bren that looked like a bren but used the L1A1 bolt and carrier and was never a semi or auto but designed and manufactured as a straight pull? Besides the body is there any restriction on using the butt slide and barrel

The actual butt slide of a Bren is not a load or pressure bearing part and you can have a box full of them so...... The laws here are just sooooooo long and convoluted with double interpretations placed on them - to suit the prosecutor of course - that to get one of what you want cleared, you'd have to........................ Have you ever heard the phrase 'pi....., er....., urinating into the wind'?

But if some wag started from fresh, using a newly made look-a-like Bren body and barrel that was a single shot crank-and-shoot 'rifle' then it'd be looked at non too kindly and THEN refused! Just my take on things

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Originally Posted by Peter Laidler

But if some wag started from fresh, using a newly made look-a-like Bren body and barrel that was a single shot crank-and-shoot 'rifle' then it'd be looked at non too kindly and THEN refused! Just my take on things

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As it stands now There wouldn't be a problem, yep they wouldn't like it, but were never keen on the lever release by Southern gun and I don't think it was just the price they didn't like.
As long as it complies to a Straight Pull, as BP points out regarding the L1A1.... had my doubts at first but there are plenty out there, a .22 Semi auto Bren would be the way to go but I'd hang fire till next month.......