Conversion to 7.62x39

[John Sukey (Deceased)]

Has anyone had success with this? I managed to modify AK magazines to work in the Bren and installed the chinese barrel, ejector, and gas regulator.
I can get the gun to feed and fire BUT it won't cycle to feed the next round.

Forgot to mention, also installed the Canadian 8mm bolt

Information

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[Peter Laidler]

John, this is a gas problem. There isn't the remotest chance in hell that there'll be sufficient gas to operate the workings AND the system. If the gas block were further to the rear it might do something but.............. we're going into the maths of it now and I've always stood clear of ammo.

Now 762 x54R would be entirely different. Bags of power in reserve there....

[csmarcher]

It would probably work with blanks if you restricted the barrel enough.

With live rounds that wouldn't work to well though..................

[jmoore]

I did a 7.62x39 conversion for a local fellow of a 7.7mm Japanese Type 99 LMG 10-15 years ago by sleeving the chamber (in retrospect it would have been "easier" to do the entire bore!) and opening the gas port to almost twice it's original diameter. It tends to "copper up" the gas system, but itseems to be OK for a day's shooting. Haven't talked to this guy in a long time, but last I heard it was fine.

Lot's o'work to get it all "happy"! Don't think I'd want to do another, but I understand that's not all that uncommon amongst Japanese LMG shooters.

[John Sukey (Deceased)]

Peter, the conversion did work for the chinese, since the bits,
Barrel, gas regulator, and ejector ARE chinese, or modified by them.
Now I do have a couple of extra return springs, and I am wondering if they used one with less coils on it. There is a point,however, where adjusting the spring might make the bolt travel back far enough to engage the sear, but there might not be enough force to strip a round and fire it, if the return spring is weakened too much.

[bigduke6]

Peter, the conversion did work for the chinese, since the bits,
Barrel, gas regulator, and ejector ARE chinese, or modified by them.
Now I do have a couple of extra return springs, and I am wondering if they used one with less coils on it. There is a point,however, where adjusting the spring might make the bolt travel back far enough to engage the sear, but there might not be enough force to strip a round and fire it, if the return spring is weakened too much.

John

Was Looking for some info and found this, click on link and scroll down to the bottom of the page were the comments are (Brock Dittrick) mentions the chinese conversion, had another page with more info but closed it down by mistake and cant find it.

Bren Mark I Light Machine Gun, Bren Mark III, Bren Mark IV

[John Sukey (Deceased)]

Read that, but it doesn't give any technical details. I guess I will just have to experiment with my spare return springs. The chinese modified gas regulator has larger holes than the .303 or 8mm one, I would think to divert more gas pressure to the piston.

It must have worked or they wouldn't have bothered.

[Peter Laidler]

It's not just the gas regulator but the barrel vent too. But the gas loss from that cartridge to accommodate/equate to the........... anyway, I wouldn't mind betting that the drop in MV will be horrendous.

We did all sorts of things to AK's (7.62 x39 again) at Shrivenham and while not quite answering the question, I use the maths/dynamics while teaching here............

Not being a pessimist John, but a realist.

[John Sukey (Deceased)]

But consider that the barrel has also been modded by the chinese. I have not miked the barrel vent.
I really am not worried about muzzle velocity since I am not going to take it to war. Just want it to work so my "friends" will stop using my .303 ammunition. Especially one of them who tends to hold down the trigger too damm long.

[John Sukey (Deceased)]

Just in passing, A friend who now lives in Tucson, Derek Kinne GC, was a Bren gunner on Gloster Hill, captured by the chinese, and deemed "reactionary"

When in hospital, an officer said to him I really shouldn't be telling you this, but you have got the GC. Still a bit out of it, he replied "Oh I was hoping for a MM"
The other GC was posthumous to an officer.