A question for Bren Gun armourers or gunsmiths

Hello, this question is more attributable to an armourer or a gunsmith who has experience in stripping a bren a bit further than the average squaddie was ever taught.
This relates to the Gas Piston and breech block carrier assembly. My question is -
How does one separate the actual piston rod from the breech block carrier? There is a locking pin in the end of the carrier which has a dimple on one end of it and is domed on the other end and I would assume that this pin can only be pushed out one way, and the reverse on reassembly. However I cannot fathom out how to push the pin out, no matter which way I try to push it, and so I am wondering if the pin is locked in place somehow and one has to do something else in order to release it and take off the piston rod.
Has anyone any knowledge of this please

Regards Rockape 26

looking at the carrier from the rear the right end is the end you need to drive it out from the end has been flared to keep in in there. The left side has a head like a nail. use a center punch to break lose the flared over end then drive it out with a pin punch. Dont tap away at it hit it hard, one good hard hit on the center punch will do the job.

When you come to reassemble it, come back and I'll tell you all about the necessary articulation and how to arrive at what's required

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Originally Posted by Peter Laidler

When you come to reassemble it, come back and I'll tell you all about the necessary articulation and how to arrive at what's required

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Peter, judging from discussion here....am I correct in assuming that one needs to always use a new pin to reassemble the piston to the carrier, I.e., the old pin having been destructively deformed should not be used again? I would assume so.
-TomH

The pin is staked to keep the piston group as a semi-permanent assembly. There should be no need to ever disassemble it unless there is damage that needs repair or replacement.

I have always used the old pin because I dont have any new pins and its not a load bearing pin just a keeper to stop the piston from rotating. When I change the piston I screw the new piston in until it bottoms out then wind back until the holes line up plus half a turn. Put the pin back in and peen over the end and finish flush with the carrier. I have to do this to comply with strange rules and regulations. I have to use a new piston when I build a semiauto to make it compliant with the laws. There is no differences in size and function of the pistons just point of origin but thems the rules.

I’ve a feeling that the pistons were shimmed to align the holes correctly.

The pistons were shimmed in order to achieve the correct amount of articulation. That is, when the piston and piston extension is inserted into the gun the piston MUST enter the conical entrance to the gas cylinder without assistance and not foul on any part of the surrounding area or the rear of the cylinder

How do I still remember this crap? Must be from when I did one!!!!!

How do I still remember this crap? Must be from when I did one!!!!! One man's crap is another's peal of wisdom Peter ... Keep em coming:beerchug:

Pete, between the Two of us at least. The Pile of 'Crap' must be the height of a
House!....:lol:

Quote:

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Originally Posted by Peter Laidler

The pistons were shimmed in order to achieve the correct amount of articulation. That is, when the piston and piston extension is inserted into the gun the piston MUST enter the conical entrance to the gas cylinder without assistance and not foul on any part of the surrounding area or the rear of the cylinder

How do I still remember this crap? Must be from when I did one!!!!!

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Where did the shims come from? I have been unable to find a part listing for them. Were they steel?

Rockape26 Join Date Mar 2018
Last On Mar-31-2018 @ 06:36 AM

Didn't even come back for the answer...

We used to make the shims from brass using a little locally made press tool.