Question on the Bren Blank Fire Barrel

[csmarcher]

On the Bren blank barrel with the heavy threaded screw on restrictor, what is the thread pitch ? (See picture)

I have bought 3 of the solid restrictors which are internally threaded and I was planning to get some shot out Mk II barrels and tap the ends so that the restrictors can be used with the blue wooden bulleted L10z blanks that we have here.

I don't have a British thread gauge so its a bit tough to tell exactly what they were using. It looks pretty fine to me, so I'd hazard a guess it was BSF , but I can't be certain.

Anyone with information, please drop me a line.
http://photos.imageevent.com/gazzavc/editingjunk/websize/rest1.jpg

Gary

[Peter Laidler]

To be honest CSM, that isn't like any blank firing adaptor that I have ever seen! Ours incorporate the whole foresight block and are threaded much further back so I'm not sure that our 'standard/EMER' Thread will be what you're looking for.

What say you KG?

[Kev G]

http://www.milsurps.com/images/imported/2012/06/Image0700-1.jpg

I have allways pressumed these type of BFA's were for crimped blank -

http://www.milsurps.com/images/imported/2012/06/LoCC7572BlankBarrel-1.jpg

The MKI BFA for bulleted (wooden) blank having the deflector plate to throw any nastyness downwards.

http://www.milsurps.com/images/imported/2012/06/BFADRAW1-1.jpg

I have seen the MK2 crimped blank BFA barrels in the UK and US but only so far on MK2 barrels and painted red rather than yellow.
Can't help on the thread type I'm afraid as I have nothing to gauge the threads.

ATB Kevin

[Peter Laidler]

Crimped blank eh....... I am of the opinion that the hole in the front of those two BFA's is TOOOOOO large to allow operatioin with crimped blank. While I don't know about, nor have I seen the internal configuration of the yellow and red BFA's but based on my limited experience as an Armourer, but the blue wood nosed blanks would simply destroy the muzzle opening of those BFA's after a very short time.

The wood nosed bulletted blank would tear the usual standard UK BFA (drawing shown) to shreds quite quickly and even shoot out the angled bullet smasher/deflector. As a result, we used to keep these 'masher' barrels in the Armourers shop where we could keep a vary eye on them. At Battlesbury, the barrels were kept nose-down in a tub of oil after use so that they could be closely examined after every exercise. Lose the deflector/smasher and the wood bullets would travel some distance before disintegrating. I don't know HOW far they'd go before breaking up. Maybe Tone E the ammo man can tell us!

I won't give you the UK type barrel thread CSM because it might lead you up the garden path and wrongly but can I suggest that you ask a local engineering shop to use a TPI gauge on the threads and you'll soon have your thread spec.

Interesting................

[Warren]

I'll check one of my Canadian BFA barrels as I have most of the TPI gauges and PM you with the spec's.
We used mainly the crimped blanks and not the wooden bullet ones in Canada. We had two lengths of crimped blanks.

[Peter Laidler]

How did you fare with the magazine spacer insert with two lengths of crimped blank Warren?
have you seen one of these BFA's?

Incidentally KG, the BFA in the drawing was upgraded in the 60's so that you could remove the guts in order to clean it as they'd quickly fill up with shi..............., er..........., debris. Identifiable by the extra 1/4 BSF bolt towards the front

[Kev G]

Incidentally KG, the BFA in the drawing was upgraded in the 60's so that you could remove the guts in order to clean it as they'd quickly fill up with shi..............., er..........., debris. Identifiable by the extra 1/4 BSF bolt towards the front

Cheers for that Peter,I'll amend my BFA notes to list that :thup:

The Canadian drawings (below) show a larger diameter thread on the barrel than the screw on crimped blank /unbulleted blank BFA's mentioned in this thread.

Canadian BFA body -
http://www.milsurps.com/images/imported/2012/06/cbf2-1.jpg

Canadian choke that fits in the BFA body -
http://www.milsurps.com/images/imported/2012/06/cbf1-1.jpg

These are the 45 dated Canadian drawings so not sure if they were ever updated in design ?
The label in the Canadian BFA box gives the part number for the BFA barrel assy as CGB403A and the choke as CGB7133.

I'll measure the choke hole size later on the screw on version to see how they compare with the Canadian choke size given.

ATB KG

[Warren]

Back to you Peter.......
Now to finish my tea and back to fixing the fence..
By the way, the long blanks did not work worth a **** with the regular mags however there was a minor alteration to the receiver with the short blanks and the mag with the insert as shown.
Kev: drop me an email on the home addie if you would........

34496

[Peter Laidler]

So was the red parallel BFA a Canadian one for short crimped blank Warren (and presumably the yellow BFA too)? If KG's drawings are anything to go by, it's a blessing that I didn't give out the standard UK thread

[Kev G]

Interesting Warren that you have the same pattern BFA too.
Just to make things a bit clearer the picture of the yellow BFA csmarcher posted is mine that was red but I painted it yellow to comply with normal BFA yellow colour !.......will have to repaint it back to red I think :-)
I have noticed a few of these crimped blank BFA's have the gun serial number stamped into the face of them,does yours Warren ? (will be in touch)

ATB KG

[Peter Laidler]

Does all this indicate that Canadian BFA's are RED?

[csmarcher]

Most of the Blank Barrels I have come across, with the exception of one, have been all over red. The yellow one, is a picture of Kevin's that I use for showing what BFA barrel I'm referring to, as there are several.

I have used thousands of the blue L10z wood tip blanks with the solid BFA's and have had great success with them. I had tried to use the short blanks, but the aperture was far too big, and consequently there was nowhere near enough pressure to operate the action.

Before we discovered the wood tips, I actually went so far as to make some of the spacers for the mags so that they would feed the short blanks, and in conjunction with a regular Mk II barrel , which we had internally tapped and used a threaded restrictor, had some success, but were plagued by inconstant loads.

The aperture squeezes down from .311 at the rifled end down to .276 so as to prevent a solid wood bullet from exiting the barrel, although with the powder load behind it, it burns up pretty well before it exits the barrel. I have shot several at some paper targets within 10-20 feet, and there is virtually no debris going beyond 20 feet. As far as flash, well you can see by the picture.

The wood tips along with the solid BFA's have been the best result. As the picture shows.............
http://photos.imageevent.com/gazzavc/camprobertsmarch2006/websize/EPV0546.JPG

[Peter Laidler]

I would guess that these BFA's and barrels are from India but that's just a guess. If you're using crimped blank BFA's then you could just drill a 1/4" hole through the barrel, down across the foresight block. Then insert a 1/4" bolt. locked with a nut. This was another alternative we used for our 7.62mm guns.

On the other hand, I suppose you COULD try a similar bolt trick across the bore to smash and shred the wooden bullet. I'd start with a 3/16" high tensile Allen bolt first. The thread should aid in shredding the wood.

There was big trouble in the 80's or so when some units had zillions of rounds of bulletted blank and the big workshop at Catterick (?) made a couple of bulletted blank barrels by welding a masher/deflector across the flash eliminator of a few old Mk3 Bren barrels in the absence of the real McCoy. They worked for a while but the energy of the wood bullet hitting the masher/deflector part just sheared the taper pin that retains the flash eliminator and bllew it off down the range............. followed by a load of 'real' wooden bullets. Apparently it was like being shot at with pencils!!!!!!!

No real damage was done and it was all done in good faith and the result on the paperwork was that '.........suitable advice should be given to those concerned.....' which in Army language means that such advice won't appear on your record but will indicate a degree of ars* kicking!