Bren Headspace - Huge?

[Grasshopper]

Hi All,

 

Warning: I'm very new to Brens.

 

I'd noticed the brass looked elongated above the rim after firing in my Inglis MKI. I bought myself a gauge to measure the location of the shoulder of a fired case. It measures .025" over the high limit!

 

Now I'll look through my barrels and see if I can find something with a shorter chamber using a headspace plug gauge. That is one place to look as I've only used 1 barrel.

 

Then there is the locking piece. Mine looks factory (81 years old). Marked JI (I assume John Inglis), the letters "RD" and the numbers 3056. My luck is the pickings for replacements are getting slim. Even then if I've a 1X size and go to 3X size it will only drop the headspace 0.008". Better but still seems huge if the shoulder is moving .025".

 

Barrel locking nut seems to snug on the barrel. Bolt looks good but I could dig out another and see if that works. All else fails I could try to make my own locking piece. With that said, anyone know the hardness of that part?

 

OTOH, I've only had one case separation and the gun spit out the casing and kept running. Maybe in the future with reload, just size pushing the shoulder back about .004" and I see if the brass survives.

 

Any thoughts or things I've missed, help would be appreciated from those that know.

 

Thanks all,

 

Grasshopper

Edited July 1, 2021 by Grasshopper

[DINK]

Bear in mind that the .303 Brit is a rimmed case and the headspace has nothing to do with the shoulder of the case. It headspaces on the rim. I don't have first-hand info about the Bren, but in my Lewis the chambers were "generous" because military firearms must be reliable above all else and a loose chamber allows the gun to digest a lot of crud or substandard ammo without choking. The original owners didn't give a fart about reloading, so they couldn't have cared less if the casings got stretched out while being fired.

 

In my Lewis, I had to full-length resize the casings because of the way rounds are held in the magazine, but you can probably get away with partial resizing in the Bren. I could get two reloads out of a .303 casing and then they would start coming apart and weren't worth trying for a third. FWIW

[Grasshopper]

Hi Dink,

 

Good point. Headspace is one thing. A "generous" chamber on the rimmed case is another. I'll try to size a few cases w/o pushing back the shoulder and try them in the barrel/chamber. If the rim goes to the breach end of the barrel, the barrel has a large chamber and headspace is likely ok.

 

I'll be happy to get 2 loadings/case. My Maxims don't do any better. I'm thinking of using pulls from 7.62x54R for the 303. I've got buckets of 7.62x54R ammo (purchased at about 5 cents/round). I can't get bullets for the 303 for that!

 

Thanks,

 

Grasshopper

Edited July 1, 2021 by Grasshopper

[BillyDixon]

is your BREN a reweld reciever ? perhaps a problem if cut between lock shoulder and bbl lock,,, just wondering

[DINK]

I bought a bunch of 7.62x54R "tracer" heads from Polygunbag Inc. a while back and they worked just fine in the .303 Lewis. They didn't trace, of course but they made a nice big flash if you shot them at a steel plate, LOL.

[jim c 351]

I Don't know anything about BRENs but when I bought my Lewis I anticipated early case failures.

Not true. I'm getting 5 reloads out of a case, then pass them on to a Enfield shooter and he gets another shot or two.

I'm loading 175 gr m72 match bullets at 2200fps. PRI factory loads hit 2450 fps.

Perhaps that's why cases last longer for me.

Jim C

[DINK]

Jim;

 

What brass are you using? A lot of the casing I was reloading were Winchester, from ammo produced for military use during WW II, which might account for my poor results with reloading them.

[jim c 351]

Dink,

You just hit the nail on the head.

I was given some WRA43 cases. They were the worst. One loading and cracks showed up.

They were the exception. RP, WIN, & PRI were great.

Jim C

[DINK]

I guess that explains it. Wartime production for a non-US cartridge was probably not held to the highest standards. Thanks

[Grasshopper]

Thanks everyone,

 

Where else can you find out information about this old hardware.

 

BillyDixon - 1940 Inglis C&R.

 

Jim C 351 - Those M72 bullets 308 diameter?

 

It digests Privi 174gr FMJ, Privi 150gr Soft Point, S&B FMJ. Will not shoot S&B 180gr soft point. I've about 300 rounds of the S&B 180gr SP to figure out what to do with.

 

I'll look into bringing down the velocity about 250 fps to help the brass life when I start reloading for the Bren. I'm learning. Still measuring stuff.

 

Take care,

 

Grasshopper

Edited July 2, 2021 by Grasshopper

[jim c 351]

Grasshopper,

My M72 bullets actually measure .309.

My Lewis barrel was brand new.

Accuracy is great and no erosion problems. I baby the gun, 2-3 shot bursts, no drum dumps.

If I should outlive my supply of M72, I would use regular 150 gr ball, .308 dia.

Jim C

[johnsonlmg41]

Could be the wrong shoulder (different cal. or too big or small of a shoulder), the wrong bolt (different cal. and there are different lengths) or just a bad barrel?

You can remove the firing pin, turn the gun upside down, chamber a round and measure the "space" with a feeler gauge. If it's too sloppy try another barrel and check it out.

The ZB platform is pretty forgiving.

I forget who has locking shoulders, but I'd check BRP and apex for spares? Maybe sarco? Unlikely that it would be a locking shoulder piece, and yes they are hard/heat treated and the screw should be staked in. HTH

[Grasshopper]

Hi johnsonlmg41,

 

Great thought. I'll get to that after the 4th holiday for sure. Seems everyone is out of shoulders except for BRP. I may pick-up one of each of the two flavors they have left and a screw to put in the spares pile. (This hobby turns you into a pack-rat.)

 

BTW, is there ever enough difference in bolts to make a difference. I've only 2 spares but will be checking them. I'll clean the grease off a few other barrels and check with those also.

 

Thanks,

 

Grasshopper

[MGMike]

Actual headspace is a function of the variables in five different components: the receiver, barrel, bolt, locking collar, and locking shoulder-- plus the ammunition itself, the rim thickness of which can vary quite a bit. Any of them can change the headspace. But the Bren is remarkably tolerant; the worst that can happen is a separated case, which you'll discover when the gun unexpectedly stops, and the next round won't chamber. Then try swapping out any one of the above.

 

M

Edited January 28, 2022 by MGMike

[Grasshopper]

Hi MGMike,

 

Have to get back at it with the Bren. I did find someone selling the locking piece very reasonably. The down side is that you could not order a specific size. Ordered 12. Found 4 that were significantly larger than what was in the gun.

 

I was worried about removing the piece as it appeared to be factory staked in a C&R gun. Turns out it was loose!

 

These are normally staked in place. Has anyone tried some loctite products. I don't have spare screws (yet).

 

Grasshopper

[MGMike]

Well, it should not be loose. If you're going to war and your life depends on it, you can stake it again, but otherwise loctite will do just fine. Just keep an eye on it by checking it occasionally.

 

Truthfully I wouldn't worry too much about headspace. The worst that can happen is separated cases, and they are not dangerous, just a nuisance.

 

I'd be more concerned about having a nice, firm fit between the receiver, barrel and locking collar. You don't want the barrel wobbling, but you also don't want to struggle to lock the barrel in. There is a sweet spot which you'll find with the right combination of parts.

 

M

[Grasshopper]

Hi MGMike,

 

Yup. I've the barrel nut selected to just be snug on latching.

 

I plan to reload the brass so I'd prefer to keep it from stretching too much You could see a line on the brass above the rim/belt for in impending case head separation. That is what started me on the quest to adjust the headspace on this old MG.

 

Thanks for the help,

 

Grasshopper