54R Bren Issues

Greetings all: I have a MKII rebuilt by Len Savage. It's in 54R. Had a big issue with it today. Took it to the range and had several blown cartridges and then.... it fired out of battery and blew up (more specifically, blew the mag right out of the magwell and about 15 feet from where I was shooting. Seems to me that the barrel is cut to allow a part of the round to be unsupported and it further seems that it is exactly in that spot that the rounds are blowing out. This was happening before and I sent it back to the builder. He replaced the barrel and it is still having this issue. Ideas?[IMG][/IMG]
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He's chambered an existing barrel and now the extractor recess is too low. The cartridge shows two shoulders as if the 303 is still there and then the 7.62x54 was done.

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Originally Posted by browningautorifle

He's chambered an existing barrel and now the extractor recess is too low. The cartridge shows two shoulders as if the 303 is still there and then the 7.62x54 was done.

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Can anything be done? Or can a new barrel be cut w/o making the shoulders too low? Unlikely you're going to find an unissued Bren Barrel, so I assume they all start cut for .303 and then have to be reamed for 54r.

As in adding on to the back? I can't do it...maybe one of these guys has a solution. Give it a minute. Peter will be along...he's done a few things with these.

Thanks Jim. Builder just doesn't see it. Seems obvious to me that the cases are not supported there and that they blow out. Although only 5-6 of the 200 I have fired so far have, I think he's relying too much on the case wall.

He is. It's the sort of thing you see when amateurs ramp their .45 barrels or other pistols for easy feeding of non round nose bullets. They end up with a blow out exactly like yours. His is a bit shocking to me when I see he just ran in the ream. OOPS!

That's pretty ugly right there.

The double shoulder is just nasty.

For the STEEL -cased ammo to have blown out at the web indicates that there was WAY more pressure after ignition than is healthy for gun or driver.

Find a REAL gunsmith and get the "LEADE" of the barrel, just forward of that "interesting" chamber gauged up.

IF the 7.62 x 54R reamer did NOT cut its full "leade" then, on ignition, the projectiles may well have been "held" a little firmly, with the associated "spike" in pressure.

Also, beware of "interesting" 7.62 x 54R ammo: some of the stuff out there may well be "safe" in the Russian or Chinese machine-guns for which it was loaded, but would produce results like yours in a barrel that does not provide full support.

Also, check how hard the extractor (if you still have it) is "gripping" the case and whether it has been "adjusted for the fatter Russian cartridge.


At least you can play with such fun toys..........

My only experience with an absolute and total bodge like this is a Vickers modied to take 7.62 x54R steel cased ammo. Extractors widened to take the slightly wider base rim diameter. Chamber reamed to take 7.62mmx54R. But the old forward section of .303" chamber remains and shows on the fired rounds. BUT, it seems to 'work'....... in much the same way as an old land-rover 'works'

I'm not sure that the extractor way is not too low but put my money in BinO's house in that the ppressure inside the case is far to high and as such WILL take the line of least resistance and pop the unsupported side of the round. It will not do this with a .303" round.

I would try 7.62mm x54 brass cased ammo and ..........., well, see what happens. On the other hand, I would only do the job properly in the first place.

Looking at a couple of extractors and spent cases I suspect that the standard .303 extractor wouldn't be a problem dealing with/supporting the 7.62x56. The breech block will have had to be machined to accept the slightly larger rim dia though

Guys,

I converted a MKII to shoot 54r. I have had no problems. I reamed the barrel myself and modified the Breech block as Peter noted. Before reaming I drove in a plug so that when I reamed I had a correct chamber, no double shoulders. Over on the WeaponsGuild Board many of the guys have used the 54r conversion with the double shoulders with no problems and there have been no reports of blowouts such as djandj has experienced. There have been case separation problems which have always been traced back to excessive headspace.

I would definitely check the headspace before I went any further. If the case gets too far back it probably will blow.

The blown-out case appears to have a very short or no "solid" section at the rear of the case. I'd be very suspicious of the ammo being used. After one blow out, another should never have been fired until the problem was solved.

Below are two pics of a cartridge in a .303 bren barrel . One is a .303 British (left) and one is a 7.62x54R (typical Bulgarian light ball silver tip) in a rechambered Bren barrel. The .303 is fully supported in the extractor cut-out. The 54R maybe slightly less but it is steel.

I'd be looking at headspace issues or ammunition. I doubt the reaming, double shoulder or not has anything to do with the problem, My 2 cents.

Joe

Thanks Peter. The entire point of the build is so I DON'T have to use a dollar a round ammo! Going back to brass 54r is not the way I want to go. This SHOULD be able to use the cheap Russian stuff. To make things more confusing, I did fire over 100 rounds with NO problems and NO case issues (I checked the spent casings) So..... ammo variance could be part of this, but.... Without proper support, no casing can support the explosion.

With the varying posts, I'm confused and don't know which way to go. Can the low spot be welded up and fixed?