Ammo types and the semi auto Bren

[AmEngRifles]

I wanted to start a conversation, and possibly a data base, no matter how limited, associated with the semi auto Bren. The purpose is to possibly come to some conclusion on what types ammo work best in your particular gun.

As I have several semi auto Brens, I will talk about this from the perspective of each individual gun and build at a time.

I had my Project Guns Bren MkIII at the range yesterday with some British, WWII Mk VII out of one of those typical wooden cases of 288 rounds. It was packed in individual 32 round boxes. I am not clear where this ammo is produced, but the headstamp on the case has both "GB1944" and "VII". I figure this is corrosive ammo, so clean accordingly after use.

It ran fine as I used my MkIII custom barrel on setting 3 on the gas regulator. Decided to try gas setting "2". Immediate case head separation, right about the rim, so the chamber pretty much has a full brass case stuck in the barrel. BTW, my barrel has good headspace.

As I policed the previous brass cases that had fired, I noticed that all the necks were displaying cracks and splits in the neck. Nothing from the shoulder down. So my question is, does this old ammo become more brittle with time? Is there something in the composition of the powder or primer that leads to brittle brass?

I had just been firing this rifle with HXP from 1975 and that ammo worked beautifully. The cases all come out nice and I am able to actually reload those. No apparent brittleness.

I am also wondering how changing the gas setting may have made the cases extract slower (?), leading to the case separation. Don't see how less gas could make the case extraction quicker? That may not be what happened at all, but wondering why all was good at setting 3, then went sour with setting 2?

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[AmEngRifles]

Interesting side note, which will not be 100% accurate but hopefully have some validity. Thru a quick conversation with a friend in the UK, a woman, I mentioned to her that I had been shooting my "Bren" gun with WWII ammo and the factory was in Leeds. She is in Yeadon, near Leeds. Batley is a town near Bradford, also near Leeds. I think it would have been the Greenwood & Batley manufacturing concern, had a large factory near the airport (or airbase for WWII) and the roof was covered in grass and cardboard cows, to fool the Germans. Well, the company is still in business, and they are an engineering concern, having made hydraulic pumps, small train engines, other sorts of go gear...they are STILL IN BUSINESS! I wonder if they have any of their WWII ammo on display on the lobby?

[SNAFU22]

Hi AmEngRifles. I have only shot new production Wolf bimetal in my semi Mk3. This ammo has a boat tail bullet that does not play well in older bolt actions, but cycles and shoots fine in my Bren. Just a thought. Has the regulator been drilled oversize? I would think that the smaller holes would be modified, as they are not useful on a semi. The only concerns I have heard for the cordite ammo was mostly about hang fires.

[browningautorifle]

So my question is, does this old ammo become more brittle with time?

Yes it does. Most older ammo will do that. .303, 30-30, .30 cal and 30-40 Krag have all done that to me. It was suggested the acids in the powder were separating and cause the deterioration...

The only concerns I have heard for the cordite ammo was mostly about hang fires.

That would be from primer issues.

[ActionYobbo]

All mine run fine on hxp, ppu and reloads but are a bit sluggish with A80 and hunting ammo. I have used lots of different WW2 ammo with the usual problems that make it a task to shoot but I generally use the .250 primer stuff in the bolt action rifles and save the .215 and .210 primer stuff for the brens

[AmEngRifles]

Thank you all for your responses.

BAR, that is a reassuring if not timely information. I will now proceed to use up my WWII era ammo and enjoy it. I should hope that split necks do not lead to burst barrels?

Snafu22, as far as I can tell, my gas block is not drilled larger. It has run fine on setting #3, since modifying the return and striker springs a bit. I do not know Project Guns history or approach on Bren builds. All I know is the one example I own. I do know Len at Historic Arms does drill gas cylinders, as my MkI has a unit with drilled holes.


Action Yobbo, I WISH my Brens ran on Wolff or PPU. I had this same issue with a Historic Arms Bren and even visited Len over the gun's functioning. He blasts those makers for his Bren builds. Says the casings are too thin. I tend to believe him, as he cut some in half to illustrate. Even with barrels in spec and head space, I still get case head separations with those commercial types of ammo all the time. Count your blessings if your gun runs fine on them. Most current commercial makers are not making war time ammo, for Vickers, Brens and Lee Enfields. They are making ammo for the Lee Enfield only, pretty much.

I am limited to HXP, MEN, and mostly any British, South African or Commonwealth made military contract .303 for the semi auto action. I have avoided using the older WWII era ammo, as I have to do the "double clean"...hot, soapy water, then dry and use modern bore solvent then oil the whole thing down. I hate rust.

[SNAFU22]

Hi AmEngRifles, I would not question your builders advice. But for me, so far, no issues with Wolf (WPA) in my home built. I run surplus 8mm and 308 in my beltfeds, so nothing against surplus or corrosive. I was late to the Bren game and *good* surplus 303 was as much as the new stuff. In the words of another "your milage may vary"

[browningautorifle]

I will now proceed to use up my WWII era ammo and enjoy it. I should hope that split necks do not lead to burst barrels?

No they don't, it just means that brass is salvage now.

[ActionYobbo]

AmEngRifles you comented on my ammo use and said gun but its guns
and they all run perfectly. It really comes down to the quality of the build.

[AmEngRifles]

I am moving on to my MkI Historic Arms Bren next. Have sold the Mk III. I will miss it greatly. I loved the shorter barrel. Just can't find them any more. I did keep my very beautiful Mk I.

Will run the surplus British WWII fodder, some HXP and some MEN, just to confirm once more that this is the right stuff for MY Bren. Then I got a brilliant idea (in MY head anyways), and want to try it out on the PPU and Wolff ammo.

What will happen if I use Rem Oil and spray a light coating over those PPU and Wolff cases before loading and firing? I am curious to find out. Is this a BAD idea?

I was recalling that so many early machine guns had oilers are part of their mechanism. I understand that early guns lacked initial extraction. I know the Bren has a healthy extraction process, by which the bolt pivots on the empty case to break adhesion from the chamber. I am wondering if with this commercial stuff, oiling it would help it break free of what seems like excessive adhesion, leading to those case separations.

Will it hurt anything? It will be a great parlor trick for range time if I can get Wolf and PPU to run in the silly thing...BEAUTIFUL silly thing.