54R Bren Issues

[Peter Laidler]

That is an ingenious way of ensuring that the gun cannot fire unless the breech is fuloly closed Joe. Is that your invention or the standard semi-auto norm? The hammer part of your hammer block is acting the same way as the hammer part or what we call the 'hammer face' of the piston post in a standard gun. The piston post and your hammer cannot hit the striker with sufficient force unless the breech block is fully closed/locked. It gets better too because even if the breech block isn't fully closed in your method (or the standard piston post method0 and you decide to close it manually somehow, it still won't fire due to insufficient energy remaining within the hammer to initiate the primer.

I know it's a bit anorakish but keep thinking to myself that if we could get 6 or so UK and US/Can et al Bren forumers together in a classroom together with a few scrap Brens, paper pencils and a black-board we could solve this problem in an afternoon and all go for a beer in the evening. Are you game Tankie and Skippy........, between us we've fixed a zillion of them - and know them inside out!

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[Joe H]

Peter,

I started building my first Bren semi in 2008. I bought the striker from one of the "Professional Bren Builders" . The upper tab was flush with the face. I began to get concerned that the design really had no way to prevent out of battery discharge. No one seemed to have any problems nor did I with .303 British and standard .303 Bren mags. As people began to build and convert to 7.62 x 54r a few problems like Djandj's began to appear. Most could easily be traced to loose headspace but a few indicated problems with the carrier not closing properly. I became more concerned and in 2011 reconfigured my strikers as shown above. I posted my ideas on The Weapons Guild Forum. I don't know if anybody used my idea or not or if somebody else had already thought of it and was using it unknown to me. There are more than one design variations around. There is another type of striker design which could be on djandj's Bren (can't tell from his pics) that utilizes a striker spring that is not on the return rod and eliminates the buffer which may have the proper out of battery safeguards. There also is a hammer fired variation. The one I built was the typical design used by most individual builders.

"Professional" Semi Bren building is pretty much a cottage industry here in the States with a number of us individuals building our own. As you are probably aware there never has been any testing done to any real extent on the semi designs. Nothing like the 100,000's of rounds and years of design that went into the original ZB/ Bren design. I for one am totally impressed with the Bren design and I'm happy to a least have working semi-autos.

Joe

[Vincent]

Attachment 62355

The striker is from another Historic Arms Bren with issues.

[Joe H]

Attachment 62355

The striker is from another Historic Arms Bren with issues.

Vincent,

What are the issues? 7.62x54R like Djandj's.

Where does the striker spring go. Is it on the return rod or is it a separate spring & rod that bears on the upper striker tab. There is an offset between the upper tab and the face of the lower section but since the upper section is the full width of the striker it's hard to see exactly where upper section hits the FP. It looks like it can't go past the upper projection of the bolt just hitting the FP.

I notice that there are no lands on your striker or on the carrier (see comparison below). The original carrier has lands that run in the grooves in the receiver. I read a write up on HA that indicated that they removed the lands and grooves from one side of the receiver. Are there lands on the other side of the striker & carrier?

Without having the gun in hand it's hard to comment why yours has issues. HA has been
building semi Brens for quite awhile so it's hard to find a flaw, if any, just by looking at parts. Have you questioned Historic Arms about the issues?

Joe

[Peter Laidler]

The actual un-machined block looks too light to be reliable Vince - although I'm just saying how it looks from here of course. I think that I would hollow out that block and weight it with molten lead to give it more inertia to do its job. But it's all making a bit of sense now. You game to solve the 7.62 x54R bren problem once and for all Vince......? Followed by a few beers?

[TactAdv]

The actual un-machined block looks too light to be reliable Vince - although I'm just saying how it looks from here of course. I think that I would hollow out that block and weight it with molten lead to give it more inertia to do its job. But it's all making a bit of sense now. You game to solve the 7.62 x54R bren problem once and for all Vince......? Followed by a few beers?

.....after a few beers in the shop, I'm thinking you pour it full of solid gold. Or DU. ;-)

-TomH

[djandj]

The actual un-machined block looks too light to be reliable Vince - although I'm just saying how it looks from here of course. I think that I would hollow out that block and weight it with molten lead to give it more inertia to do its job. But it's all making a bit of sense now. You game to solve the 7.62 x54R bren problem once and for all Vince......? Followed by a few beers?

Hey guys, I'd be happy if you could just solve MY 54R problem, much less all of them (lol) And I'd be buying better than beers.

---------- Post added at 09:20 PM ---------- Previous post was at 09:19 PM ----------

Attachment 62355

The striker is from another Historic Arms Bren with issues.

Funny, my Historic Arms internals don't look like that. A bit different.

---------- Post added at 09:29 PM ---------- Previous post was at 09:20 PM ----------

All,

Below are pics of how I altered the semi striker so that the rifle could not be fired "out of battery". These are pics of my rough prototypes to show how it works. The second pic shows the set up at the instant of firing. The length of the firing pin and tab offset have to be coordinated so that tab cannot hit the FP unless the carrier is in the full forward position. About 1/4" must be left clear to the rear of the tab so that the recoil buffer will work.

Joe

WOW Joe - you are way ahead of me on that. Yes, the gun does blow up usually on the first round of the mag (after manual racking). However, here in CA I can only put 10 round in the mag at a time. I have a wooden dowel in there to take up the rest of the room. Here are some more pics of my innards for you.




But from the damage to the casing (and the mag) I keep thinking that it fired out of battery or something like that. But usually only one out of 60 rounds.

[Peter Laidler]

DU....... there's a thought!

[Vincent]

You game to solve the 7.62 x54R bren problem once and for all Vince......? Followed by a few beers?

I am game, Peter. Double game for the beers.

----------

Joe,

The picture is from this thread Anyone have a Wise lite arms Bren it’s on the second page, but some of the posts on the first page are worth reading.

[WallyG.]

The striker and carrier design used by Historic Arms does not have a left hand side key/land. This feature is part of his denial of full auto parts modifications. The left channels of the receiver are filled with several weld plugs and made flush. The other side of the striker shown in the picture has the key/land machined into the side. As to insufficient inertia... the design uses a very large compression spring which seats into a pocket milled into the rear of the striker and passes over the center recoil rod and terminates against the rear slide wall. Oddly, to maximize the size of the striker spring... but still have enough room for its recoil compressed form - Historic Arms removes all of the slide buffer parts and has the striker spring seat in the pocket that remains after their removal. I've never had a failure to fire for lack of striker force and the extra striker spring seems to compensate for some of the missing buffers recoil absorption. I have not yet crushed a striker spring or battered the slide face.