Bren Gun: Help Needed!

[Flying10uk]

I think that this must be about the first time that I have seen a screw thread sectioned, picture 4, something which I was taught was never done.

[scoobsean]

Wow! I did not even realise this. Please tell me more about this feature. It that is the case, I will try to procure a new Mk1 pattern carrier.

Also, the firing pin retainer/pin does not want to budge out of the bolt body. Is that normal or are the ends peened in?

It pushes out one way but not the other (I can't remember which way though)

[Brit plumber]

Push on the machined end with the dimple, the premed end will then protrude outwards.

[Peter Laidler]

OOOOOOOOOOps......... No need to worry Meerkos........ I was looking at the wrong part geometrically and mentioned the wrong fault so to speak. I say don't worry, but that doesn't mean about the dire state of the machining and where it is machined. The section that plays a most important part I mentioned is still intact. It is the small ramp that you can see in photo 4 with two little lumps at either side at the right hand end.

As the piston extension slides to the rear, the first 3/4" or so this ramp tightens up the extractor stay which transforms the extractor from being slightly articulated into becoming rock solid with the breech block and therefore grip the rim very tightly. This is COMMENCE TO UNLOCK and is part of another feature. During the next stage, the breech block will START TO UNLOCK and drop down at the rear, rotating about the front breech block stops. This causes the tight extractor - which is locked solid to the breech block - to tweak on the fired case and break it free from the tapered lock. That is the end of mechanical safety and the breech is free to open fully rearwards

Very simplified - but there you go. Your extractor stay ramp is still intact

What the sectioned thread part does illustrate is the complicated Mk1 piston (simplified in the Mk2 version) of having longitudinal ribs between the piston rings half way down the stem that cover the gas vents in the body - for reasons best known to someone in the universe somewhere which means you have to have an indexed thread and therefore more complications........ Total waste of time and only done because the licensing agreement said so! Deleted at the first opportunity for the simpler and just as effective Mk2 piston

[Brit plumber]

Thank you for your insight. This is indeed amateur work. I'll be honest, I have no intention on any serious machining work on this piece, but thanks a lot for the proposal B.P.
This Bren has close to no real collector's value, since no numbers match, the finish is poor, and the integrity is ruined by amateur work. I will give it a good clean, a nice coat of linseed oil on the wood, and wax on the steel, and that would be it. It would make a nice wall hanger and mechanism demonstration unit, but that's that.

Don't be down hearted, you can add value and aesthetics with a little work, the fact it is non matching would encourage me to improve it as you can't really devalue it. Tidying the cuts, a fresh coat of a semi sheen black paint with
Red high lights and it will look 100% better. You have the benefit that most of us forumers will never have. You have a Cutaway gun that you can cycle rounds through, there can't be many like that in this world. I doubt there's even one in the US. Regardless of what you end up with, it's still a Bren.

[Meerkoos]

OOOOOOOOOOps......... No need to worry Meerkos........ I was looking at the wrong part geometrically and mentioned the wrong fault so to speak. I say don't worry, but that doesn't mean about the dire state of the machining and where it is machined. The section that plays a most important part I mentioned is still intact. It is the small ramp that you can see in photo 4 with two little lumps at either side at the right hand end.

As the piston extension slides to the rear, the first 3/4" or so this ramp tightens up the extractor stay which transforms the extractor from being slightly articulated into becoming rock solid with the breech block and therefore grip the rim very tightly. This is COMMENCE TO UNLOCK and is part of another feature. During the next stage, the breech block will START TO UNLOCK and drop down at the rear, rotating about the front breech block stops. This causes the tight extractor - which is locked solid to the breech block - to tweak on the fired case and break it free from the tapered lock. That is the end of mechanical safety and the breech is free to open fully rearwards

Very simplified - but there you go. Your extractor stay ramp is still intact

What the sectioned thread part does illustrate is the complicated Mk1 piston (simplified in the Mk2 version) of having longitudinal ribs between the piston rings half way down the stem that cover the gas vents in the body - for reasons best known to someone in the universe somewhere which means you have to have an indexed thread and therefore more complications........ Total waste of time and only done because the licensing agreement said so! Deleted at the first opportunity for the simpler and just as effective Mk2 piston

Thanks a lot for the explanation. This is a well thought-out system. I do agree that the work done to this Bren leaves much to be desired.

---------- Post added at 08:02 AM ---------- Previous post was at 07:59 AM ----------

Don't be down hearted, you can add value and aesthetics with a little work, the fact it is non matching would encourage me to improve it as you can't really devalue it. Tidying the cuts, a fresh coat of a semi sheen black paint with
Red high lights and it will look 100% better. You have the benefit that most of us forumers will never have. You have a Cutaway gun that you can cycle rounds through, there can't be many like that in this world. I doubt there's even one in the US. Regardless of what you end up with, it's still a Bren.

Thanks for the reassurance. I will try my best to restore this old gal. Again, I am extremely happy given the price, but objectively speaking, there are issues. I will give the wood a light sanding and oil coat. Are you sure paint is the way to go? Or can I use cold blue solution like Oxpho?

[Peter Laidler]

As for the finish I suggest that you look up METAL FINISHERS in your local trade or engineers directory and get the whole thing chemically blacked. It is a chemical etching/staining process that is far more durable than any paint.
To be honest I would not be the least bit concerned about the lack of matching numbers because these numbers only relate to the barrel, barrel locking nut and butt slide when it is a working service gun when the numbered parts must remain together for technical reasons. For your gun this feature is totally academic. Remove them all except for the master number on the top rear of the body.
I would not do anything to the butt and pistol grip except give them a coat of darker stain and soak them in linseed oil. It looks like they have been sanded to death already. You could LIGHTLY sand the carrying handle and oil that.

It will make a good conversation piece if it's done well and properly. But it is your Bren

[Meerkoos]

As for the finish I suggest that you look up METAL FINISHERS in your local trade or engineers directory and get the whole thing chemically blacked. It is a chemical etching/staining process that is far more durable than any paint.
To be honest I would not be the least bit concerned about the lack of matching numbers because these numbers only relate to the barrel, barrel locking nut and butt slide when it is a working service gun when the numbered parts must remain together for technical reasons. For your gun this feature is totally academic. Remove them all except for the master number on the top rear of the body.
I would not do anything to the butt and pistol grip except give them a coat of darker stain and soak them in linseed oil. It looks like they have been sanded to death already. You could LIGHTLY sand the carrying handle and oil that.

It will make a good conversation piece if it's done well and properly. But it is your Bren

I'll try to look for local people who have such equipment. Just to be sure, what you are referring to is hot salt bluing, am I correct? Or is it more of a parkerization? Also, I can try rust bluing the whole thing myself.

As for the wood, as you said, I will even consider replacing it. The grip is badly cracked and the stock's edges are all marred. Do you know where I can find a replacement?

Thanks for your advice!

[Flying10uk]

It's very rare that new old stock wood seems to turn up, that I've seen offered for sale, for the Bren. If you can't repair and use what you have, I would say that you would most likely have to look round for good second hand replacements.

[Peter Laidler]

If you try to blue it it's an amateur job. If the professionals do it - it's a professional job! As I am not clairvoyant I cannot tell what process your local engineers use. It's your gun, do what you want. Your gun is an inert display piece. You don't need new wood. Just make good what you have without degrading the wood any further.