Bren Gas Cylinder

[tankhunter]

Joe,The bottom line is this. Any Bren is a GAS Operated Weapon Sysytem. If you have eliminated any possible Binding of the working parts. A simple check by allowing the gas piston extention to run back & forth. Lightly held at the back of the ejection slot at the rear with a finger. It should move freely with no binding at all.

The do the SAME, WITH. The breech block mounted on the piston extention afterwards.

When this condition has been reached, & if you are sure that the extra strain of compressing a striker spring Etc is still a difficulty.
Then there really is only one thing you can do. Enlarge the gas port in the barrel & gas block.
Do this CAREFULLY, a tiny bit at a time. As you can remove metal as required. But you cant put it back, so to speak! Ream a little at a time, reassemble & test fire at port 2. Until she functions flawlessly!

If you are STILL unable to get it to function correctly. Then there is only one component left. The Gas Regulator! Spares are plentiful your side of the pond I believe? You MAY also have to ream the gas port/s a LITTLE to get her to function at setting 2. Thereby leaving you plenty of 'Reserve' power should you need it.

To give you an example of how this was done. The now Obsolete (Sadly) 7.62mm L1A1 (FAL) Semi-Auto Rifle. Had a mod if required in this same direction. The first stage was to ream out the gas block & barrel gas port at the same time. Stage one was: use a 2.6mm Reamer, straight through till it entered the barrel. Then ream to 2.7mm. IF Required. Stage 2 was: Ream the same, to 2.8mm, then ream to 2.9mm.

You see how LITTLE metal was required to be removed to get the rifles to function correctly when 'Tired'?

In THEORY: The gas port in the barrel SHOULD already be large enough to enable a sufficient reserve of gas. Should you need to move the gas reg. The CHEAPEST method of the above suck it & see method. Would be to FIRSTLY ream the gas Regulator ports. As THIS is the CHEAPEST & SAFEST method of modification. A Gas regulator is cheaper & easier to replace than a Barrel, should you make a mistake!...

If you think about the Bren's design. there is also a Buffer mech at the rear of the Butt slide. This was to cussion the recoiling effects on the piston extention assembly. If the designers at BRNO put this setup in the original Bren design. It was there for a reason. As well as a buffering effect (Slightly) on felt recoil on the gunners shoulder. It should be borne in mind. That it also was put there to cussion the effects of the working parts hitting it. Why? because it was designed in the first instance with a gas port of sufficient size orginally. To drive the working parts rearwards with a gas port of maximum diameter.

It's a GAS OPERATED Weapon. If it does not function/cycle correctly after curing any binding. And also, The Breech Block clears the ejector Etc. It is a GAS Problem. (Use known GOOD Ammo as well!)