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BREN gun semi-auto build...vintage sniper? 1.5 MOA groups. VIDEO UP!

Forgotten Weapons just posted a new video on the Bren, havent watched it yet...

Edit-just viewed the FW episode, its part one of a series of 3 on the Bren from pre war to the 7.62 models.

Apparently early on a direct fire optic and telescopic sight were planned, in addition to the open sights. After Dunkirk, those plans were scrapped.
 
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Your project looks fantastic! I have an excellent condition BREN MK 1 parts set I would like to use to build a semi-auto but I cannot find the Shotgun News article online and no one seems to be making the semi-auto parts with instructions anymore. Would it be possible to get a copy of the article from you from you so I can start my project?
 
Here my L4A3 I just built from a kit, very cool guns
 

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Actually haven’t been on here in years, was doing a google search trying to get some info on a semi auto Bren striker and this thread came up, along with another useful one on calguns, machined a striker and finished the gun and felt right to share it here on this awsome thread
 
Actually haven’t been on here in years, was doing a google search trying to get some info on a semi auto Bren striker and this thread came up, along with another useful one on calguns, machined a striker and finished the gun and felt right to share it here on this awsome thread
And stick around! Even if only in Vintage… the Gentleman’s corner of SH!
 
Wow, the Bren took me back, first fired a mk3 in about mid 1965/6 in the Army Cadets, cut my teeth on a mk4 lee Enfield and shot on a military range about 8/9 times a year plus a 2 week summer camp. The Bren came out on camp and about 3 times a year at the range. Loved both of them. Used the Bren in its 7.62 LMG format whilst serving, but not very often.
Thanks for the thread a great piece of engineering
 
My L4 parts set is in my "to do" pile.
Wrapping up my MKI double dovetail Bren in 303.


Finally getting some play time and work done on my Bren double dovetail MK1. I opted to grab a BRP center section which cuts down the built time ( for me) quite a bit. Cut the gas cylinder section to length and milled both the center section and cylinder and welded them together.

Rear receiver heel was cut a little wide and thru the take down hole. Its welded and needs cosmetic clean up but I focused on the internal section.
The bolt and carrier do the "tilt test" and travel freely by its own weight. I built my DPM and RPD the same and they run super smooth.

I am envious at how fast some guys can knock projects out and I am just happy so see some cool builds and squeeze one in when I can.

 
Its one piece again.....progress !

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Its the little stuff......

Bren selector denial / selector stop.
Nothing fancy but wanted something simple that does the job and looks decent. Turned a piece of stock , punched a hole thru the ID and cut a segment off and TIG welded it in place.

I also have more segments for my other builds.


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My MKI Ben wood is a new manufactured set I purchased from the UK ( D&B Militaria)

Not sure if they still stock them but this is another source if someone is looking for correct MKI wood.

https://formriflestocks.co.uk/product/bren-mk1-set/


Wood is walnut and looks to be manufactured to correct specs. All the cuts are clean and sharp. Everything lines up and is on center.
The walnut has a nice grain and will look awesome after some oil is applied to it.


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Firing pin transfer pin finished and will be heat treated this week. Its skeletonized as much as I want to go and will give it a test when hardened.
I slotted the bar for roll pin clearance for .080" max forward travel and zero rear.

A good carbide drill is what you need to drill a hole thru the bolt~

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Post cleared for added transfer bar and retaining pin.

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Rear stick out~

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Top~

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Bottom~

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Putting all the pieces together to test fire.....

New wood is nice and fits perfectly.
I was missing a pin for the rear swivel so I had to turn one.

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Test fire day tomorrow !

I wrapped up making my "Lime" flavored striker group per print.
Striker is made from 4140 heat treated to 50Rc C , guide rod is 0-1 and tubes are stainless steel.

My MKI was a partial parts set missing a lot of small items and the farther I got the more parts I found out were missing but I think I got all of them now.


When I put firing group together and racked the slide and dry fired it I really thought the striker was weak and not going to snap a primer. To make sure I pulled a Wolf .303 round and chambered it and gave the wife and grand kid in the other room a heads up. It want "BANG" with a nice primer strike.
I had a big smile and they looked confused / condition normal.

The impact force and spring rate is deceiving and will find out tomorrow if it cycles.
Turkey day is coming up and I need to vacate my favorite work spot.

Pile of striker parts~

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Test fired primer hit , very robust~

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If it runs then I make it pretty~

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Discovered a slight issue before test fire.

Racking the slide by hand and making sure everything slides smooth with no drag or binding I discovered one area that needs minor fitting.
When I test snapped the primed case I lightly squeezed the trigger until the striker let go and lit it up. Cycling by hand and getting a feel for the trigger operation I noticed my striker was dragging on the disconnect. It was more noticeable when I applied a full and firm trigger squeeze. The added trigger squeeze put more pressure on the disconnector and the edge of it was sticking up higher and really slowing the striker down.

It was an easy fix by taking some material off the leading edge of the disconnector and polishing its contact surface. I will test fire it but the weather is total crap today and do not feel like lugging the Bren out in the rain. I might take some more material off the disconnector to reduce more drag.

You just need enough surface to reset the sear as the striker passes over the top.


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At least it looks good on the tripod~

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Background info on this rather early and unusual Bren Mk 1 (copied from another site): ~ (source IMA-USA.com)

"The British Expeditionary Force was evacuated from Dunkirk in late May and early June 1940 under severe pressure from the German Wehrmacht. They left most of their equipment, including the new Bren Gun, behind on the beaches; so that virtually all Brens in existence now are of post-Dunkirk manufacture. Not only that, but at the beginning of July, a directive was executed indicating that a number of time-saving changes were to be made in the design, and these resulted in the Mark I Modified (Mk I/M) on August 21 and the Mark II right after on September 4. In other words, the Mk I essentially ceased to exist right after Dunkirk, and much of what had been manufactured before Dunkirk was lost, making the Mk I receiver a genuine rarity.

IMA has obtained a very small number of original Mk I receivers dated 1940 and has made them into parts sets. The Mk I is distinguished in several ways from all later receivers: the left side of the receiver has TWO vertical dovetail slots. The rear slot is for the drum sight, while the front slot is for an indirect-fire dial sight. The right side features a prominent reinforcing rib at the rear of the magazine well; the top front of the well normally has two oval lightening dimples. The top rear of the receiver was beveled to remove additional weight. These features were abandoned to simplify and speed manufacture. Lastly, the gas cylinder section of the receiver has complex lightening cuts, and the gas shield has a concave groove on the front to control exhaust gas direction.

However, it would appear that the changes were not all done immediately. We have found an Enfield (E in D) logo marked receiver that has characteristics of both the true Mark I, and the Mark I* (modified). This receiver has the second sight dovetail, as well as the reinforcement on the other side of the magazine well. The gas tube is deeply fluted in the typical early MkI Style. However, the "dimples" at the front of the magazine well are absent, as is the beveling on the rear of the receiver. In all likelihood, this is a receiver that was in production as the changes were being made after Dunkirk, and the last lightening cuts were omitted. A fantastic bit of history for any Bren collector.

In conversation with a British Bren aficionado, he told me there were approximately 2000 of this type of Bren made."


...I don't know squat about Brens, but I find this thread and these two restoration projects incredibly impressive.
 
Incredible thread, thanks!

I just watched the 2019 version of Danger Close, really good, I liked it.
BTW, there is a 2017 movie called Danger Close, but it isn't about Aussies in Vietnam.

I will have to check out the other movies listed.
 
I am claiming victory after battling with minor issues that makes the difference between a working gun and a paperweight.
I have learned a LOT about Bren's and the MKI during my build which will help me moving forward.


The fit , alignment and everything on my MKI go together smooth as silk yet I was having problems getting more than 5 shots out of it consistently.
That started with it being a single shot that when I made changes and thinking I solved the problem/s only to discover something was still not right.


My MKI has the original gas cylinder , piston and carrier that measure and fit as new. I know about the gas loss with the MKI and the change to the MKII gas cylinder but that was not any of my problem/s.

My biggest issue was getting the disconnector to reset consistently and not making a huge drag on my striker movement forward or aft.
I put a relief radius on the disconnector with reduced surface contact / drag that helped but still did not fix my problem.

What I learned from looking at the stock Bren carrier and lower frame is the original designed gun used a flat pad on the piston post bottom to trip / reset the disconnector for semi auto fire. When a striker block is added behind the carrier you are now eliminating that piston post resetting the disconnector and that role is now done by the striker block.

On my gun it took a fair amount or force to reset the disconnector which put drag on the striker / not good.
I isolated that function and extended the bottom of the piston post by the length of the striker block. I also slotted the bottom of the striker block to clear the disconnector.

This removed drag and any returned the reset function to the recoil cycle of the carrier and piston post , like the original gun.
BIG difference on my gun and function.

I used key 3/16" key stock and made the height the same as the stock piston post reset area~

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Stock Bren disconnector reset function~

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Stock with striker block added~

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Extended reset area on piston post bottom~

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Slotted Striker Bottom to clear disconnector~

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NOT working~




After Mods....it.....is .....alive.

 
That and adding drag to the striker forward and back which helps nothing.
 
For those with the Want, but without the drive to build....
 
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Great thread. Good job both of you on resurrection of these old girls.
I got to play with a couple of brens in the army. L4’s while on exchange with the poms and an original.303 back in Australia, we actually had two in our armoury. We had a few vickers guns too.

Danger close is a good movie. I had a couple of blokes that I served with that were technical advisors on the armour side of things.

I saw a question about the Aussie use of the M60 vs Bren. The M60’s were very widely used, the Brens did see some use too. We still had the 60’s in the system when I was in but thankfully they phased them out about three years into my time. They were replaced with the MAG58’s, known as the M240 in US service, GPMG in Brit service and correctly as the FN MAG.

My particular baby was the MG3, we ran them on our tanks at the time. We were using the German leopard 1 (AS1) which was armed with MG3’s. Surprisingly enough those beasts were superbly accurate. However the best MG for accuracy that I ever shot was the L4. They could shoot the arse off an insect at 600 yards.
 
Does anyone have info or resources to refer to for converting from .303 to 7.62?

Friend in Australia (and with the licensing, wants to make sure this is doable before he runs the paper, spends the money) has a chance to buy a partial .303 Bren. He'd prefer to mod it to an L4, and can get all the parts, but is concerned about the magwell.

FAR too many "dremel till it fits" and he'd much rather have machinist instructions, diagrams, specs, etc. instead of ruining the expensive, no-longer-made, and papered receiver.
 
Some days it pays to get up early!!!

Just scored a WW2 Bren Tripod with T&E. and antiaircraft leg kit. BRP Corp. spam e-mail this morning that I only opened because they had a Nepal BIRA gun. But that was priced stupid. But I snapped up that tripod like a python in a bunny cage! They sadly only had one...

Been looking for one of these for ages!!!

Now that's a great way to start Independence Day weekend! Or Ungrateful Colonials Day as they call it in Birmingham.

Cheers,

Sirhr
 
Saw the same email this morning, bira gun is cool, wonder how many rocks they smoke a day there
Sadly with interesting guns being a great inflation hedge it’s probably not too far out of the market. Compared to a few years ago that tripod was priced insane. But tripod prices are higher than gun prices!
 
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