Need help with semi auto L4A4

Greetings to you all.
I have contacted some of you privately trying to gather some of your expert opinion and unfortunately I am still looking for answers. I have an L4A4 bren which since acquiring it has had case head separations. It is a Historic Arms build which I have returned to them and they had it running on Radway Green ammunition. I have been unable to get more than 5 rounds down the pipe before having case head separation or other case ruptures causing a jamming issue. I have tried to headspace the gun to the best of my ability and it will close on a go and no go 308 (to be expected), but will not close on the 7.62x51 max case length gauge. I looked through the instructions that Sarco supplies with their new production barrels to check if the fit is correct and everything seems to be in order regarding correct spacing/gaps and lock up etc.
I have tried surplus remington from the 60/70s, 70s lake city, new production lake city from 2020, reloads, and all have had issues.
The gun will not cycle on gas setting two and will sometimes crack cases, but usually not have a separation. On 3 the gun will cycle, but almost guaranteed it will have a case head separation.
More information, the components are mostly enfield original parts. The barrel is enfield as well as the bolt and carrier if I remember correctly. I don't recall the receiver, but I don't think that matters for this.
A weird not is when doing a chamber casting following
Since the gun headspaced correctly I am starting to wonder if the gas system or extraction process is somehow causing a violent extraction.
If anyone has any information or ideas that could help I would greatly appreciate it. I scanned the forums back through 2015 without much luck.

I am going to suppose that the case separations are being caused by too much friction between the ejecting case and the barrel chamber.

Have you confirmed that the barrel chamber is within service specifications? Bore erosion at the throat might have widened the bore and the expanding case lip might be deforming when fired to a condition where it's front is wider than its rear - causing too much extraction drag/friction and the resulting neck separation.

I have over the years obtained several .303 surplus barrels her in the US that look fine but are "shot out" and cause the same separations that you describe, Unfortunately finding a "replacement" .308 barrel will be a challenge. Is your barrel a true/original UK .308? Was the gun built specifically for it? Is the bolt an original UK .308 bolt? You would be wanting to try a new barrel to eliminate the variables that the current barrel might be introducing into the equation. If the barrel and bolt are original UK .308 then trying to test other calibers to eliminate possible component issues will be more of a challenge.

As to gas settings... semi auto's as a general rule require more gas to cycle... compressing the additional striker spring(s) and cycling more steel (striker is a new addition to the internals that are reciprocating). Len typically enlarges the barrel's gas port and also drills out oversized the gas block and one of the adjustment settings in the gas nut. Can you confirm that this has been done? I would not expect the now semi auto gun to cycle completely on the 2nd gas port - especially if the components have not been drilled out oversized to deliver more gas to overcome the new springs and mass of the semi auto internals.

What solution are you seeking?

Unless there is something to be done to the parts that you have already, new components will need to be found and substituted and function tested to see if the flaw(s) can be identified and eliminated. Again, this will not be any easy path if your gun was built using original UK .308 parts. They are not easy to find in the US and when found are expensive.

Those cases look rough. The chamber might be causing them to stick.

A case separation isn't from excessive gas, it's from an oversize chamber. Excessive gas can rip off a rim however, stuck cases will rip off a rim... I doubt the manufacturer is starting with new barrels and just because they parkerize them and make them look new doesn't help. If your chamber is fat it can rupture too. I had lots of case separations over time with machine guns, all excess headspace issues.

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Originally Posted by browningautorifle

......just because they parkerize them and make them look new doesn't help.

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Yes. Listen to THIS.

“Parkerizing” is nothing more than phosphoric acid etching of the metal surface. As it is intended to do it causes microscopic pitting of the smooth surface. Among other things, this in effect causes the surface to become rough and porous, obviously no longer smooth much less polished.

Parkerizing a barrel chamber is -ALWAYS- a very bad idea!!!

Fortunately, it is largely reversible and easily fixed by liberal applications of something like FLITZ metal polishing paste, applied by fully coating a rotary mop (I use a cotton shotgun chamber cleaning mop, appropriately sized to the chamber you are working.) and placing the shaft of the mop on an appropriate extension and powering it with a portable hand drill, Dremel tool, etc. Use medium speed and make sure the FLITZ paste never dries out while turning.

Go CAREFULLY.....you can EASILY remove a .001” of metal quickly!! All you want to accomplish is to polish out the microscopic porosity left from the Parkerizing. It does not take much time to do this.

Once you have removed the porosity and restored a smoothed, polished finish you will likely find your case sticking issues are resolved.

You WILL discover you have increased the overall chamber bore dimensionally a very slight amount which SHOULD not be a problem.

Also.....all this being said above....you did not mention whether or not your .308/7.62 barrel is original military (guaranteed chambered correctly originally), or a new-made aftermarket tube.....where no explicit chambering dimensions are necessarily guaranteed. If new-made I sound almost CERTAINLY expect it to have been cut to SAAMI-spec .308Win chamber dimensions, and NOT to military-spec 7.62x51NATO dimensions, which would easily be a problem as you describe if it was SAAMI cut to minimum chamber dimensions which are ALWAYS intended for bolt-action rifles for maximum accuracy.

If you have a new-made tube, and you’ve tried the after-Parkerizing Polish to no avail, locate a COMPETENT person who can re-cut the chamber using a proper 7.62NATO reamer.
-TomH

Sorry for the delay. Very busy. I appreciate all the help and will try to get back to your help as soon as possible.

As far as I am aware it is all original military. Barrel is marked Enfield. All bolt parts and carrier appear to be Enfield as well. It was originally a converted Mk2 by the UK military to an L4 when they were switching over to 7,62x51. After it was cut upon entry into this country it was rewelded by Historic arms. I do not see any aftermarket parts other than the SA conversion parts. I do not have throat erosion gauges to measure and do not know how to measure the rest of the chamber. I gave it my best to headspace the gun with the gauges I have and it seems OK, but I'm sure there are other variables to check as well. Closes completely on 308 go and no go, but will not close on 7.62x51 max gauge.
I assume the gas ports have been reamed per Len's MO and the gun will not work on setting 2, but will on setting 3. This corroborates that thought as well.
When I sent the gun back to HA for a look over I think he polished the chamber, but I cannot recall. I do see the rings on the shoulder of the cases which is odd, but I can't imagine this is causing enough sticking. Len had said that he had it running like a sewing machine on Radway Green ammunition (can't find any), but everything else I have tried thus far has not worked. I have not tried steel cased (don't want to), still need to try PRVI x51 and many other European surplus rounds to see if they will work. Too bad everything is out of stock and costs an arm and a leg. Lake city 2020 and other US surplus from the 60s and 70s hasn't worked, nor have my reloads. All rupture.
I have been waiting for SARCO to get their barrels back in and I will buy one of their parts kits with it to get extra parts to try.
As far as quick things to check that will not cause much damage and then working up to potentially destroying parts to fix the issue, what are my first options to check out what could be the problem? I could try polishing the chamber, but if anyone has a way to measure the chamber first to see if there is in fact an issue first, I would greatly appreciate hearing how that is done. The cerrosafe I have expands too much and I was told it is not a good surrogate.
Any input on first steps for checking or fixes would be appreciated. I'm leaning toward trying to polish the chamber first, but I would like to hear everyone's opinion on what would mess up the gun least first. Am I understanding correctly that the South African barrels will not work in the L4? Those are the only ones I can find readily available. Everything else will be aftermarket SARCO barrel.

What solution are you seeking? - A working firearm that will not have case ruptures.

Thank you all again for help in this matter. I have been hitting my head against a wall trying to figure out what to do.

It should not close on the .308 No go gauge !! Your head space is off !! Sarco .308 barrels are short chambered . Historic Arms rewelded the receiver and did not allow for normal bolt and locking shoulder set back and that why you have incorrect long head space . There are many Historic Arms Bren's with all kinds of problems which head space is one . You need to change the the locking with a large/longer one to correct the head space so that the bolt will not close on the no go gauge and the cases should not separate.

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Originally Posted by tr63

It should not close on the .308 No go gauge !! Your head space is off !! Sarco .308 barrels are short chambered . Historic Arms rewelded the receiver and did not allow for normal bolt and locking shoulder set back and that why you have incorrect long head space . There are many Historic Arms Bren's with all kinds of problems which head space is one . You need to change the the locking with a large/longer one to correct the head space so that the bolt will not close on the no go gauge and the cases should not separate.

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It is NOT a sarco barrel. It is an original UK 7.62x51 which if I'm understanding correctly may still close on 308 no go without issue. It wont close on the 7.62x51 max gauge.

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Originally Posted by SleepyDoc

It is NOT a sarco barrel. It is an original UK 7.62x51 which if I'm understanding correctly may still close on 308 no go without issue. It wont close on the 7.62x51 max gauge.

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I understand it is not a SARCO barrel , Believe me it should not close on a .308 no-go gauge .

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Originally Posted by SleepyDoc

It is NOT a sarco barrel. It is an original UK 7.62x51 which if I'm understanding correctly may still close on 308 no go without issue. It wont close on the 7.62x51 max gauge.

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Thats a sarco barrel. They copied the profile from the South Afrcan barrels which is different from the English barrels. Also who ever populated that barrel cut the lugs of the sight base instead of milling the slots in the barrel because thats easier to do than a bit of milling (lazy lazy lazy)
I am telling you straight that that is a sarco barrel (American made replacement) but you can have what ever fantasy you want.
BTW that gun was never a Mk2 as you said but it was a Mk3.

Polishing a chamber will take metal off and increase the headspace problem, not help. You have a headspace problem. It should run with all ammo not some special ammo that you can't get. RG isn't something godsend, but you can't try it so it's out. US issue ammo should work fine. Work towards a headspace that's tighter and your separated cases will stop.

Good eye on the missing front sight lug...this implies that a flash hider was grafted to a barrel... an original has the locator tabs on each side - also barrel looks too thick to me to be UK - in profile forward of the gas block and its missing the locator lug on the underside to mate with the receiver. OP When you say its marked "Enfield"... is that actually spelled out in a stamping? UK contract barrels have multiple small proof stamps and a used barrel would also come with one or more serial numbers struck in it as well. All should be stamped between the barrel seat and the carry handle. If this area is sterile... lack of markings and the profile deviations mean its most likely a new production barrel. So... Suspecting that this is in fact a SARCO barrel... the case separation solution still resides in the dimensions of the headspace and the chamber... you need an experienced gunsmith to assess both. As for locking shoulder and bolt... if the bolt is a real .308 it should be marked as such... can you provide images of the bolt markings? Original .308 barrels use specific bolts and locking shoulders because the breech face is a different geometry than for the .303 guns. I presume the SARCO barrels are made to the .308 breech face dimensions and not .303. Also, there could be receiver dimensional issues when welded back into semi form... again an experienced gunsmith will be needed. I wonder if the bolt is hitting the bolt stops before coming into contact with the case - producing too much headspace. if welded up slightly off in the mag well dimension/length this can come into play and no new locking lug can adjust for the bolt bottoming out on the stops prematurely. Anyone else have any more suggestions? Unfortunately, most of the implied issues are not easy for a DIY user to remedy. Good luck!

I guess this is my fault for not including more pictures initially. The barrel is as described. original UK, Enfield manufacture.
I was wrong. Never should have trusted my memory. It is in fact a Mk3, converted to L4.
Bolt is also Enfield.

Not ideal to have it close on a 308 no-go, but considering the 7.62 max is the MAX for a 7.62 it is theoretically still safe. I would prefer a tighter chamber and I could have the barrel altered to set the chamber back, but I wanted to try less destructive things first. Something like polishing the chamber. If that or other less destructive methods don't work then I can have the chamber set back and re-check headspace. I will probably need a gunsmith to do the latter for me for safety concerns and so I don't mess up the whole barrel. There is enough room from the receiver to the locking block to do this at present time.

I will try to find some throat erosion gauges or measure some spent brass cases to see if there is excessive expansion. The chamber does appear to have more scratches and irregularities than I remember as is evident on the cases. It is hard to believe that would cause anything, but weirder things have happened.

If anyone else has recommendations on how to polish the chamber or what tools to use, please let me know. Any idea what size of shotgun mop would work best? Is flitz the best to safely polish without taking off too much material? I saw someone use a mop or something with high grit sandpaper, but that seems a little much to me.

If anyone has other ideas I would also like to hear them before going down this rabbit hole.

I can also supply any other information or pictures if it would help someone to make another diagnosis or figure something out.

Thank you all for your help in this matter. I will update you as I make alterations based on your input. Given my terrible schedule right now it might be a bit to get something done, but I will try to keep you all in the loop.

I would like to see how you are going to set back the chamber to cure your long head space ? Are you going to shorten your barrel and use a .308 reamer to rework the long head pace ? If you do the barrel locking treads will need to be reworked the locking nut will be in trouble , the gas piston will need to be shorten, the gas block on the barrel will have to be relocated because the barrel was moved rear ward . You only need to do is change out one item and that is the bolt locking shoulder with one that longer it is held in with one screw !!! Stop making you chamber longer or larger in dia.. What are you taking about when you refer to 7.62 max. as being safe for a Bren in .308 cal. ? What 7.62 gauge I hope not the one for 7.62x54r .

Anyone have a source on 308 locking shoulders? I will have to measure mine. I know 303 guns have various sizes, but it seemed at a quick glance that 308 guns were not the same. Basically the ones I have found don't list a size. it is just a part with no guarantee if it will help my headspace. Any information or sources?

Max headspace gauge:
https://www.forsterproducts.com/pdf/...2018_print.pdf

Stolen from another forum:

Headspace lengths for caliber .308 Winchester
1.630" GO
1.634" NO GO ??????????
1.638" FIELD REJECT

The G.I. Headspace Gage lengths for 7.62mm
Go Gage...................................... 1.6355"
NO Go Gage................................ 1.6375"
Rebuild Maximum Gage.............. 1.6415"
Field Reject Gage....................... 1.6455" (MAX)

As I said, max headspace gauge for a 7.62x51 chamber. Yes, I know 308 and x51 are similar. As I understand it SAAMI specs are still different. Please correct me if I am wrong. My gun headspaces within the max gauge I have, but it doesn't necessarily mean it is appropriate for the gun. Obviously something is happening. Still trying to figure out if it is purely headspace or something else. This is why I am asking for help in trying to figure out things. If I can find a locking shoulder that fixes the problem, then great. I didn't have to destroy any material. As of right now I know the headspace is somewhere between the max 7.62x51 and 308 no-go gauge, so it may only need a small correction to fix. However, I will have to work up the algorithm at some point to make other modifications if that doesn't solve anything. I.e. if it isn't actually a headspace issue and polishing chamber, or other part changes may be needed. There are lots of things that could be wrong, and lots of ways to fix those problems. Heck, you could drill it out and sleeve the chamber if you wanted to correct the headspace issue. There are near infinite possibilites of things you can do. Doesn't mean I want to do them or should do them. If I could find a barrel for a reasonable price to swap out and try I would do it. I will start at the locking lug which seems easiest and work from there.

I will repeat, I am definitely not an expert an am still learning about the intricacies of the L4A4. Some of the things I may say may seem silly, but with what little knowledge I have they seem appropriate as of right now. As I learn more that will change.

I appreciate everyone's input and I at least have a starting point to start the investigation. I will try to order a few locking lugs and see if I can get lucky with one that is longer. Hopefully there is a good return policy. After that I will see what the next step is. Since people keep adding input my steps may change base on practical and less invasive measures then work up.

Gun Parts Corp. has locking shoulders .they do not sell them by size . They are selling them around $10.00 or less they all so have the locking shoulder screws to go with them .You can buy 3 or 4 and see what you get luck of the draw . Get a couple of the screws as well . You well need a good fitting large screw driver to remove the screw . The screw head it is located under the mag. latch . Pull the retainer pin for the latch and the ejector they will lift out , you will now see the head of the locking shoulder screw . Secure the your receiver in such away that you can apply force with two hands to the screw driver to remove the screw . note: the screw is staked to prevent it from shooting loose . With the screw removed the locking shoulder can be removed and you can measure it for length . I would wait un till you get your parts from Gun Parts Corp. before you remove your existing locking shoulder. hopefully you will get a locking shoulder that is longer/larger than the one in your Bren presently . If you have a replacement that is longer than the one in the gun you can install it and recheck the head space ,the bolt should not close on a field gauge but close on the go gauge . Note : A too long locking shoulder can be shortened by using a surface grinder . This is best done by a gunsmith that has worked on a Bren gun and understands it's workings . When you do the final locking shoulder install the screw must be re-staked to insure the locking shoulder will not shoot loose !!! Can you use or know how to use a digital calipers to measure the locking shoulder ?

Bren locking shoulders... I don't think it's a good idea to drill out a chamber and try to set in a sleeve.

30: Bren Locking Shoulder (SIZE 2) - BRP CORP

Bren Locking Shoulder - SARCO, Inc

L4 Bren Locking Shoulder, 7.62mm NATO, *Good*

I ordered 6 locking shoulders and 3 screws from Numrich (e-gunparts corp). Their return policy should let me return an envelope of parts weighing less than 1lb for free within 90 days or so. I also ordered another firing pin so I can make another one if needed. It also helped me to get enough in the cart for free shipping. I can only assume since multiple people have told me to get any locking shoulder that it should be the same geometry roughly. Finding an original 308 marked locking shoulder will be tough and some of the places you gave me links to were out of stock anyway.

I will measure mine then the others and if I get a longer one I will update you all with what the headspace gauges show. Hopefully Over the next month I can get it all put together and maybe find some time to trudge through the snow to make some holes in paper for you all. Preferrably without case ruptures this time.

303 locking shoulders will all be to big for a 'standard' L4A4 and if grinding down will probably need re-surface hardening.
Have attached info on locking shoulder sizes for reference.
303
Attachment 114785

7.62
Attachment 114786

As others have said this is not an Enfield or Interarms barrel but would be interested to know how many grooves the barrel has ?

Not that it has anything to do with your problem but S/N A5197 shouldn't be dated 1967 as it was a batch of 180 L4A2/L4A4's dispatched to Weedon in March 1960 ?

Regardless of the history of the gun based on serial numbers, I have semi-good news, gentlemen. I received six locking shoulders. Of which some of them were marked enfield 66. All of them had numbers on them, but I don't care about the numbers, I care about the size. The aforementioned locking shoulder measured in at 0.816. My original locking shoulder came in at 0.811. After doing some more looking to make sure I was headspacing it correctly and a few tries I can safely say that the gun no longer closes on the 308 no-go gauge. It will close on the go-gauge if that wasn't implied well enough.

This is only semi-good news because I am in the midst of the glacial Wisconsin winter. We have more snow than I care to traverse to at present time, so I will update you all later with function testing. I have longer locking shoulders which might also work if I have to polish the chamber later. I have all the way up to about 0.829, but most of the others are around 0.821 in.

If anyone else wants to discuss history of the gun while waiting for an update, feel free. I know nothing of the gun other than it doesn't work and it has stamps that say enfield. I appreciate any and all information. If anyone has info on HA and whether they have a habit of stamping things to make it appear more official or whatever else may have happened, that would also be appreciated. If anyone knows where this formerly LMG may have been deployed that would be great to know.

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Originally Posted by SleepyDoc

measured in at 0.816

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That should do it, looking forward to hearing the test shoot results.

I tried to reply to your PM but it the forum isn’t working properly at the moment.

Disregarding the issues your having with head separation/splitting cases, the originality of the gun is questionable. The serial number is the correct format but the actual number is bogus. That A5 part dates to very late 1959 or very early 1960, when I first read your number I assumed it was an L4A3 but even that doesn’t fit as an L4A3 with that A5 serial would be from 1965 not 67. My other thought was that it may have been a very late Mk3 serial number but to be the last of the Mk3 guns it would need to have a UE60 pre fix (also there’s the 1945 date on the body so it cant be a late Mk3 gun).

A genuine L4 would also have the original Mk3 number barred out where your new number is located, the UE number should be above it. Then there’s the markings them selves, they look narrower than my examples and I suggest unequally spaced. I think they are hand stamped, very well done but not the wide and relatively deep pantographed marking of the oriiginal.

What I suspect is, that this gun is an ex Indian DP Mk3 made into an L4A4 using some parts from a L4A3.

Regarding your cases, I think your heading in the right direction. A few other things to check, the gas hole in the barrel (often opened up to compensate for a warn cylinder). Also check the fit of the bipod on the cylinder, it should be loose. Also check what type you have and have a look for any DP marks. And while your at it, check for any SAF markings which are Indian.

Don’t be put off by any observations or comments, at the end of the day you want it to run and it doesn’t really matter if it was once this or that.

To confirm what has been recently observed. HA did/does in fact mark up sterilized (old markings filled in with weld) guns in the style of the version that is being "reconstructed." Many demil cuts destroy original markings and the reweld process can do further damage. He does use hand stamping with a jig and a tool that holds multiple characters in a straight line for stamping all at one. Only Len could tell you what he might have thrown together in the mixing bowl to create this semi auto "representation" of an L4. Finding a semi Bren in the US with all matching numbers from an original gun is a rarity (unless it is still an registered full auto before beng converted to semi) - as to build one you would first have to have a complete demil kit with all of its original parts. I'm not saying that it doesn't happen or hasn't happen but I've seen a lot of demil Bren kits over the years and most of them are a hodpodge of parts - yes the receiver bits are typically from the same weapon but rarely are the rest of the "kit's" components.

And when KEV G chimes in on Bren specifics... his words are golden.

Good luck with your trouble shooting. Not that it means anything but trying the locking shoulder fix is a good start from my perspective. Also...

Have you tried to install a regular 303 Bren magazine in the magazine well (without the 7.62 adapter installed)? I know you don't have the .303 latch et. but as a test of the length of the reweld of the mag box area if you can get a .303 mag and it does fit (tight/loose etc.) then this will at least potentially rule out possible mag well length dimensional deviations in the reweld process. There are also dimensioned drawings available that with some tedious measurement could tell whether there are any hidden dimensional issues present in this particular reweld. As reassembled parts they are all a bit different even though a jig is used to graft the parts back together. These are two additional diagnostic paths that might prove revealing.

Thank you for the information. I have zero knowledge on this subject and am new to the forums, so being a naturally skeptical person I don't know who to trust yet. Given multiple people are telling me the same thing, and after looking through more of the forum I will gladly accept your inputs as truth. The authenticity or origin of the gun doesn't bother me at all. If it was mocked up to be a facsimile of an L4a4, then ok. As long as it goes bang then I don't care. Sometimes it is just nice to know where things have been though. I don't see any Indian markings off hand, but will more investigating on the matter. If HA welds over old markings then it is possible those could be gone too. If I remember I will try to measure the gas port when I get a free moment.

I do not have any 303 mags to check at present time. Hopefully in the future I will have a 303 Bren too. I can tell you that the 308 mags are fairly tight. Not excessively, but they don't wiggle. If the locking shoulder doesn't do the trick I will dig further into the receiver dimensions. I may have to just go do a function check at a nearby indoor range instead of going to the outside range. It is currently single digits or below 0 Fahrenheit here. In the mean time I will try to get this thing scrubbed out and a fresh lube/grease job to make sure I can't blame anything on friction or dirty parts.

I think that you are on the right path with the new locking shoulder installed and the bolt now closes on the go-gauge and will not close on the no-go gauge . I have seen a number of Len Savage's rewelded Bren guns with head space problems ,most all were corrected with the locking shoulder adjustments .

One item to check might give some clarity on where your gun's receiver started life (on the Bren gun evolution scale). See if the inside walls of the mag well are pierced by actual mag lip support shelfs - which are on an original A4 part of the disc that is riveted to the side walls of the receiver. I am guessing that it started out as a true Mk3 and there are no mag lip supports piercing the receiver body to hold up the front mag lips. Also notice that that the model notation stamping is shallower that the adjacent A4 notations - a result of blasting and refinishing in the rebuild process - hinting that it really was a Mk3 gun body before an A4 parts kit was used to complete the conversion from .303 to .308. If an original the I'd expect degradation to all markings and not just the model inscription. I also think the Enfield D and 1945 are original markings to the receiver - normal demils tend to not destroy these areas of the receiver, but the serial number location on the rear upper flat is usually heavily damaged by the torch cutting. The serial as marked is in the format but as previously noted.. the time period it indicates is not right. Also... finding a barrel with the exact same notation (font and size) would be very interesting and from my observations a bit unexpected. Also.. the barrel is devoid of the small stampings generally found on UK contract production... various proofs and inspection stamps.. also steel lot numbers.

Just a few observations that might shed some more light on you gun's history. Did any stampings on the outside left flat under the barrel nut survive? There is usually a two digit date stamped there.


Best wishes for your guns complete recovery!

WGH

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Originally Posted by tr63

I think that you are on the right path with the new locking shoulder installed and the bolt now closes on the go-gauge and will not close on the no-go gauge . I have seen a number of Len Savage's rewelded Bren guns with head space problems ,most all were corrected with the locking shoulder adjustments .

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In response to this observation, I have had the SAME issues on guns that came directly from Historic Arms. What I don't get is how Len can build a gun and not have headspace set PERFECTLY, from his hands to the new owner?

I have an L4 that he stated had two barrels headspaced perfectly to the gun. When I got the gun, it was a bit different story. One will just take a No-Go, but works reliably. The other appears more " generous" and has given me case separations and feeding issues. It is frustrating to be told one thing, only to find reality is a bit different.

I hope you find an appropriate locking piece and resolve your issue. ,

The question I would raise regarding Len Savages gauges then is: When were those gauges he uses, last calibrated?.......:ugh:

Well,Have you confirmed that the barrel chamber is within service specifications? Bore erosion at the throat might have widened the bore and the expanding case lip might be deforming when fired to a condition where it's front is wider than its rear - causing too much extraction drag/friction and the resulting neck separation.

I have another reply to this thread, with regards to the barrels.

I was told by Len, when I purchased my L4, that the barrels were actually 1919 Israeli barrels, that he somehow fits inside the original parts or exterior of an L4 barrel!!? Makes it sound good, as there are many new, surplus Israeli 1919 barrels available...sometime, Len will dazzle with tales of fascination and my mind wanders. Hence not recalling every detailed word he used to describe the process.

But does that make sense? Is it possible?

There are obviously STILL set up issues with HA guns, and that is becoming more and more clear as time goes by. I recall my first HA purchase a number of years back. Never could get the problems resolved and Len had it twice for R&R. In the end, they gave me a refund.

It is troubling to me that he seems to be building "models" of guns and not so much, actual operating guns. I know I am being a bit harsh, but he sells them as FIREARMS...they should run.

BTW, NOBODY is going to like this solution, but I found, with HA MkI, that it WILL reliably run PPU and Wolff .303 if I spray oil the cartridges first. Not a great solution, but allows me to save the military grade ammo, that does run reliably in the .303 (MEN & British mil spec). A different story for a different day. I have not had case separation issues with the HA MkI, unless running PPU or Wolff.

My L4 problems boiled down to too much spring pressure, inducing short stroking and jammed cartridges on feeding. That was resolved by clipping two coils from the striker spring! Thank you MilSurps Expert! Gun runs well on gas setting 3. My L4 has NOT had any case separation issues like my .303. So your issue, may not directly correspond to my issues? Different gun, different caliber??

I would say, if you chamber looks rough, I would have a tendency to want to polish in a longitudinal fashion, instead of the rotary method. Just slowly and minimally. Try to remove less metal, plus, the case is extracting along that bore axis. But I suspect you have done what polishing you were thinking about, so a late point. Not sure what tool to recommend for that? Additional or new L4 barrels are not easy to find. Hopefully, someone might do a run in the future??

For me .303 surplus barrels her in the US that look fine but are "shot out" and cause the same separations that you describe, Unfortunately finding a "replacement" .308 barrel will be a challenge.

Sorry for the delayed response everyone. I just moved to a new state, started a new job, have a new kid on the way, and am still unpacking. Additionally I am trying to paint my garage (horrible idea), so that I can have a new workshop.
Basically I have been busy.

Update:
The gun fires without case head separations as of right now. This is post locking block exchange and headspacing. Hooray!
Now I have problems with stove piping though. it is picking up a new round, but getting caught on the ejecting round. So either the ejector needs replaced or the gun is overgassed and slamming forward too quickly. It appears that on 2, there isn't enough gas still and will not extract, but on 3 it will pick up a new round but slam home on the spent case.

I will try cleaning the gun and see if it needs a good cleaning, but I may have to slightly ream out the #2 hole. Unsure as of yet. Any other ideas are appreciated at this point. I do not have the gun in front of me and I'm trying to type this fast because I should be painting, so i do not know if it is bolted or milled into the magwell for the mag stop. I will update more later and will try to get you all more answers to your questions.

At 100yds it appeared to be doing a good job of accurate fire on a horrible resting platform (bucket). Now just to correct the cycling issue.
At least we are heading in the right direction.

If the headspace is not correct nothing else matters at this point. Replace the barrel or locking shoulder until its correct on gauges then move forward.

Quote:

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Originally Posted by cal50

If the headspace is not correct nothing else matters at this point. Replace the barrel or locking shoulder until its correct on gauges then move forward.

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Yes, I headspaced the gun using a new locking block. This is why the gun fires without case head separations. I am now working on the cycling issue. I will continue to update when I can get to it again. Any other suggestions or thought son what may be causing the cycling issue would be greatly appreciated. For everyone's information it occasionally functions correctly. However, it is more likely fail still thank work.

Make sure the bolt and slide move smoothly , no drag or sticking.
Check your gas piston diameter and gas cylinder for any excessive clearance.
Are the correct springs in the gun ?

Does it fire and eject or short stroking ?

The Slick Bren MKI restoration. - YouTube

I don't recall any hiccups in the action. slides smoothly enough that I have dumped it all out the back end a couple times while disassembling, etc. It has all the springs that came with it in the gun without any alteration. From what I have seen they are correct and without alterations to them. The gun fires and will eject, but often stovepipes as of now. If you have correct spec numbers for the piston diameter etc, I would appreciate those. Otherwise I will try to find them. I have calipers and can take the measurements when I get those.

The gas cylinder ID .634" +.003".

The piston is scrapped if the head is .618" or less.

As near as I can work out, ALL L4 barrels, from the A4 onward, were fully internally chrome lined. (HARD crome, straight onto the steel substrate of the bore; NO preliminary copper plating as seen in "decorative" chroming).

Quick test: A dab of "cold-blue" applied to a bore or chamber with a simple "Q" tip / ear-bud, will provide an answer. If the tested area does NOT go "blue", it is probably a chromed (or stainless steel) surface.

Post plating, chambers can have a distinctive surface "texture". This can be moderated by EXTREMELY judicious polishing. "Super-slick" chambers are a REALLY bad thing.

My guess is that an L4A4 barrel that leaves circumferential scoring on the fired brass is less than Kosher. Ditto, one that does not have hard-chrome lining.

Sorry to keep you all in suspense (or lack therof).
I measured the OD of the piston head and it is 0.625, so should be in spec. I measured the front of the piston, behind it seems slightly larger at about 0.628.
I attached a photo of the piston on the op-rod. It isn't screwed in all the way and has a slight wobble to it. I assume this is correct because there is a pin going through it and I would guess that the pin is only in a certain spot. Please correct me if this is wrong.

I don't have cold blue at present time, but could check it in the future. For know though, I'm still on the hunt for the reason why this thing is having cycling issues. I haven't had it out in a while and will try to go to an indoor range here in early February. Following the move I no longer have a go to range, which has been making things difficult. I found a place in town which should work. However my time may soon be occupied since my wife could have our second child at any moment and I may lose chances to get this figured out.

Since it has been a while as a reminder, the problem now isn't the cases rupturing. That seems to be fixed following headspacing. The issue is either short stroking with occasional stovepipes (underpipes?), vs overgassing and the same issue. On 2, it won't cycle and pick up a round, on 3 it is jamming. Since it is having an occasional stovepipe, I assume it is overgassed on 3. I have calipers, but not sure how accurately I can measure the ID of the gas ports. If you have measurements to compare I could check those. Seeing as this is an HA gun, it sounds like they are usually reamed/drilled out a little already.

As always, I appreciate all of your help and will hopefully have this thing working again in the near future.

Greetings: It's been a while... here are some observations from my experiences to date with HA manufactured Semi Auto Brens.

1. The gas cylinder should not be wobbly in the receiver body... it should be rock solid. Why? Hard to diagnose from a distance - both physically and time since manufacture.
2. HA guns typically have the gas port in the barrel enlarged - size may vary depending on the gun.
3. Typically, only one gas port setting on the gas nut is enlarged from the standard size and that is one to "match" the enlarged barrel port - providing more gas to power the SA internals that weigh much more than the standard internals and also to overcome the introduction of the striker spring to the recoil system. Note: HA guns typically have the "as built" recoil buffer assembly removed to accommodate the striker spring length and the striker - which also acts as a recoil buffer but one of a simpler design and being physically present between the bolt and the rear of the receiver.

Different gas settings in an original Bren (once sufficient gas is provided to successfully cycle the action/internals) that provide more gas should still function but just beat your shoulder and the gun up from the excessive recoil impulse. I have read opinions that gunners used to run their guns over gassed to eliminate the possibility of a short stroke failure during combat. Too much gas should not cause feeding issues. The original gun as designed just absorbed the heavier rearward impulse force and the recoil spring returned the bolt in the cycle with the same force regardless of the bolt and carrier's recoil force level. Two independent cycles in play... one rearward and one forward.

You may very well have a damaged striker spring in your system... they can get crushed... and if damaged it might nor provide sufficient return impulse to the bolt... causing miss feeds. HOWEVER, since this is a .308 (is that right?) magazine feed lip geometry and the .308 cartridges might come into play... do you get the failures on all mags? How many have you tested in your gun?

Food for thought..

Best of luck...

WallyG.

Sorry, The op rod/piston that screws into the bolt carrier is wobbly. Not the cylinder. Seems like it should be OK, but I may disassemble it and see if it can be inserted m ore and if this will affect it at all. Will have to see how it aligns with the exhaust ports. IF you are uncertain what I am talking about due to my lack of appropriate terminology, it is the last picture I posted. The bolt carrier has a piston that screws into it followed by a pin to keep it from rotating out. That is slightly wobbly. Any adjustments to be made with regard to that piece?

Yes, 308 gun. I have shot a couple different mags, but I can work with it again to see if there is an issue with the mags. I have 11 in total, I think, so I can try to run a few through each when I get the chance. Hopefully in early February I can take all my projects to the range to infuriate me all at once.

The striker return spring does not appear to be damaged. Any idea on specs of springs I might need if I wanted to replace them?

I can try to set the gas on 4 and see what happens, but what is the risk of using the gun on 4 all the time? Am I inviting failure and breakage given that this is not an original gun? Will it be more likely to destroy parts given that the pieces are essentially fit to work instead of their original intention?

Hello:

Wobbly gas piston should not be a problem except a loose fit between the piston and the cylinder will allow gas to escape around the piston - reducing the rearward impulse and potentially requiring a higher gas setting to run the gun. This type of fit/wear issue is why there are multiple gas nut channel sizes in the original design.

I did not clearly communicate. I have never seen a gas nut where HA has drilled out all 4 of the gas channels to oversize... usually it is just one. So, when you say you are going to use setting 4... if HA drilled out channel #2 to oversize... 4 might not actually be allowing more gas than the drilled out 2 setting. You would need to determine if your barrel gas port is reamed out to be larger than as issued... and which if any gas nut setting has been drilled out to oversize... AND.. compare the gas channel sizes in the gas block itself (channel that feeds the gas nut) on the barrel to see if that channel was also drilled out oversized... all of this is just to determine if the gun has had its gas system modified to allow more gas into the cylinder to power the semi auto internal cycling. You need to find the combination of elements that allows the most gas and test this for feeding function... if max gas does not sufficiently recoil the internals to allow for reliable feeding... it could still be multiple contributing elements... spring issues... not enough gas, magazine feed lip/round positioning issues... if hand cycling the action provides reliable feeding of rounds, then running the gun should too. If not then each element(s) need to be investigated in the search for the cause(s).

"but what is the risk of using the gun on 4 all the time?" This is the scenario I mentioned regarding gunners running their guns over gassed... it can lead to damage of internals over time... in the case of a semi auto of HA design... potential crushing of the striker spring comes to mind. All of my focus on the gas channel sizes is to allow you to accurately determine what combinations really provide more or less gas... and whether the barrel and gas nut have been modified for semi auto use in a HA semi auto system. If you have a barrel or gas nut that is unmodified... this could be part of your problem in adjusting the amount of gas needed to power the HA semi design. Systematically assess each system element against a known original configuration part or specification. Good luck!

Have reread this thread in search of clues... the most recent discussions are about gas pressure and spring pressures... all potential contributors as they impact internal cycling and timing. Multiple adjustment options involved. However, if this is a Mk3 Bren receiver reconfigured to emulate a .308 L4... then there are some fundamental differences involving the bolt and associated parts, the ejector, the receiver feed lip supports, and the magazine feed lips between the Mk3 and a true as built L4 receiver. Are you trying to use .308 L4 Bren mags? A Mk3 was not set up originally to feed from these so there are potential geometry issues between the component parts of the Mk 3 gun body itself and the L4 magazines. Many of my running .308 Brens use South African .308 barrels and the Hungarian Zb 39 magazine. I have running versions of this combination of elements. Len has not always had success with Mk3 receivers feeding from L4 mags... I have one "converted" receiver that was abandoned for semi auto function using L4 mags as it would just not feed .308 from a L4 magazine. I have not yet tried to reconfigure it into another configuration of parts and calibers. Originally, the South Africans modified the feed lip supports of their Mk II's - converting the receivers... they also modified the mag wells to use L1A1 FAL magazines... and filled in portions of the receiver feed ramp area directly above the barrel... so even their engineers realized that a .303 receiver needed specific modification to allow it to reliably feed .308 rounds... and their barrels were designed to interact with all of their modifications - functioning together as a system. The HA modified non L4 receiver guns would not have received such SA modifications' and as such are a bit hit or miss in function. Like me, you may just have a dog - at least using L4 mags... using a standard .303 ejector and a Zb 39 mag may function in .308 when the .308 L4 mags do not... you'd have to try that out... more parts to obtain and test. Good luck!

Ok, so if I haven't mentioned it, I am a father (again). I have been on vacation for two weeks since having my newborn daughter and have not been able to get to the range despite having planned to do it, and even having approval from the wife. Something about newborns and not sleeping makes it hard to get motivated to do anything. Anyway, the good news is that since my sleep schedule is so messed up now I was really motivated after hours to take the measurements on the gas ports. They read as follows:

Barrel Port: could not measure
I: 0.098
II: 0.11 on one side, and 0.116 on the other
III: 0.12 and 0.13
IV: 0.145
Gas port to gun: 0.177

I will try more magazines when I get the chance.
Springs still look good when inspecting them, but if anyone has a lead on how to replace the springs to freshen them up I am all ears.

I will try to get her all freshened up and cleaned for a day I get off work early so I can try to make it to the range to give a better update for you all. Since I haven't done anything to it since headspacing it though, the only thing I can really tell you is if I can get it to cycle properly on position IV.

Any other suggestions before I make my range trip are welcome so I can test more things out at the same time.