Thanks to the folks at SMG Guns in Texas, I just got my completed semiauto Bren gun in 7.62x39mm. What the best way to break it in? Take it to a run-n-gun match, of course!
First off, the front grip is a repro experimental piece made by IMA – it would not originally have been on the gun, but I needed a way to hold/shoot it offhand.
A brief history of the Chinese Brens…
During WWII, the Canadian Inglis factory (a privately-run enterprise) made several production run of Bren guns for Chiang Kai-Shek and his Nationalist forces. These guns were chambered in 8mm Mauser, the standard round of the Nationalist Chinese forces, and were marked on the receivers in Chinese characters:
The guns used a Canadian copy of the original Czech ZB-26/30 magazine, which held 20 rounds of 8mm ammo. These guns were used in plenty of combat actions in China, both against the Japanese and the Communist factions as well. Eventually a significant number were captured by Communist units, and after the AK rifle and its 7.62x39mm cartridge were standardized by these forces, a number of Bren guns and ZB-26 LMGs were converted by them to use the AK magazine and cartridge (similarly, many Arisaka rifles were rechambered to 7.62×39).
This conversion was fairly simple. The barrels were bored out and lined with 7.62mm liners, the ejector was lengthened, and a new magazine catch was made which held the AK magazine up against the front of the magazine well. Stock 8mm Bolts and extractors were used, as they worked adequately. In some cases, a second sear notch was cut in the gas piston, which allowed the sear to capture the bolt carrier even if it failed to travel as far back as it should. The lower gas pressure from the 39mm cartridge obviously had less reserve power for operating the Bren mechanism than the original 8×57 would have. Contrary to some claims, the gas piston and gas tube were left their original size, although the gas port in the barrel and gas regulator was enlarged.
Some thoughts after shooting this converted Bren…
It’s HEAVY. According to my scale, it’s 23 pounds, which is only about 2 pounds heavier than the Madsen LMG I shot in one of these matches a few months ago, but it’s longer and not as well balanced. Great off the bipod, but I had serious trouble shooting it standing (not that it was designed to be shot that way, of course).
Recoil in 7.62×39 is trivial. It’s possible to fire 3-5 round bursts that are actually fairly effective and accurate, because the muzzle hardly moves. Try that in a .303 semiauto Bren (or any other full-power semi) and you’ll have a much larger group, or take longer to get a small one. The big rear aperture sight stays nicely in view when you shoot, and overall it’s one of the most effective and shootable “semiauto machine guns” I’ve had a chance to play with.
Malfunctions – I had three, two caused by my ammo and one by the gun. The ammo problems were one dud primer (it had a nice sold firing pin strike) and one that hit the barrel face and stopped rather than feeding into the chamber. I was using softpoint ammo (grabbed the wrong can for the match), and the Bren certainly wasn’t designed for that (in any caliber). The gun-related problem was a case that didn’t fully eject, and got jammed between the next round being fed and the side of the receiver. This was caused by a combination of a receiver much larger than it needs to be (because of the caliber conversion) and a gas system just barely strong enough to run the gun reliably. When this malf happened I was firing from the hip instead of holding the gun solidly, and just like short-stroking a recoil operated pistol, a bit of free movement in the gun was just enough to delay ejection and cause a problem.
I was very happy to find that throughout my initial zeroing, the match, and some demo shooting afterwards, I had no other problems. The Bren was obviously built to run on much more gas pressure than the 7.62×39 cartridge generates, and I’ve seen conflicting opinions on whether this conversion would work reliably, especially with the additional striker spring required for the semiauto setup. SMG did a great job building the gun!