Conversion to 7.62x39

Small Arms Review did a article on the Chinese Bren 8mm a while back but unfortunately I can't say when. It was a few years ago.

To be really honest - and diplomatic, I'd say that anyone who was seriously considering converting any of the Brens to 7.62x39 and expecting any sort of mechanical reliability was pis............er....., urinating into the wind to coin a well used English phrase

John: Two suggestions, both based on experience with other (but similar gas-operated) guns that exhibit apparent lack of energy to cycle. Neither may cure your problem but they might. I would regard them as the sine qua non of getting any gun not originally designed for 7.62x39 to work properly.

First, considering yours is a Chinese barrel, probably made in the days when clumsy conversions were improvised because China didn't have the resources to provide its troops or militia with more suitable arms: Take the barrel outdoors and closely examine the chamber with the bright Arizona sunlight shining in from behind you. If the chamber walls are anything but unfouled, white-bright and unpitted, especially down in the neck/shoulder area, you will need to make them so. If the chamber has patches of yellow-brown scum, get rid of them with a .45 stainless bore brush chucked into an electric drill. Then make a Cerrosafe chamber cast to detect any bulge, eccentricity or surface anomaly that might be retarding extraction. It's also a good opportunity to check the chamber dimensions for anything out of whack.

Second, you didn't say what kind of 7.62x39 ammo you were using, but the Chinese almost surely were using steel-cased ammo in this conversion. Brass-cased cartridges (often favored by MG shooters simply because it's usually NC) tend to be softer than steel and when fired will adhere more tightly to the chamber walls --again retarding extraction and giving short-recoil symptoms that are easily mistaken for insufficient gas.

M

The Chinese conversion of the ZB 26 in 7.62 x 39 works well, however we are looking at gas trap as compared to ported. The one illustrated in The Bren Gun Saga vol.2 works well with both steel and brass cased ammo.

Nice to see you here MGMike and hope all is well down your way.

Hmm...I have a parts kit of one of the Chinese converted Brens that I'm sending out to have built in a couple months. I've talked to folks with functional Type 99 Nambus and ZB-26s in 7.62x39, and I was hoping the Bren would be do-able as well. I guess I'll find out! I even managed to find a ZB-26 magazine converted to feed 7.62x39, in place of the more common AK mag conversion:

Unusual Chinese ZB/Bren Magazine

https://www.milsurps.com/images/impo...2mag6JPG-1.jpg

The main problem here that I see is what we call 'the twilight zone' where the round if not under control. That is neither controlled by the magazine or the chamber. That spells bad news and the perfect recipe for a jam. That;s the very reason for the major difficulties/problems converting the Bren to 76.62mm and the reason why the magazine has to be moved so far forwards. And it was this that caused the major head and heartaches. It was finally cured in a novel way........................ And not be creating a 'twilight zone'

ForgottenWeapons,thanks for the post about your mag and the link to the other pictures.....very interesting.
What are the markings on the spine of the mag ?
Are there any markings on the conversion parts ?
Have your tried any 7.62 x 39 rounds in it ? ......just wondering also if 7.92 x 57 crimped blanks would also fit ?

With this setup the rounds are further back than the AK mag conversion so the small 7.62 x 39 rounds vent off gas is going to have to work overtime to push the working parts back that extra inch to cycle the next round or to capture and hold the piston extension.....plus another inch of friction :-)

Good luck with your conversion and let us know how it goes.

ATB Kevin

I don't recall the markings on the conversion parts, and they're a bit packed away right now. The magazine (which I found separately) is numbered "186" under the front lug and has what appears to be a small stamp of three interlocking diamonds on the spine (no German markings).

I have tried x39 rounds in it, and the feed lips are a bit loose but the length is perfect. It'll hold about 15 rounds before they start to act up because there isn't any curvature to the magazine. I would be surprised if it will feed reliably with more than 10 or 12, though. Guess the only way to find out for sure is to get the gun built! :)

I really want to find an 8mm Bren barrel to go with the kit, so I can shoot either cartridge.