54R Bren Issues

[Joe H]

Dandj,

Removing .004-.005" off the LS (or off the back of the bolt) will be a real pain in the a-s to do by hand, but probably the safest way, if you are not comfortable with setting up and using high speed machinery. You will need a perfectly flat surface, I use a piece of plate glass and some emery paper or a good flat stone.

I would do the LS. If you can get access to a disc sander (grinder) it will take just a few minutes. If the table can be rotated, depress it 25 degrees, if not make a ramp out of wood or whatever so that the LS bottom face sits 25 degrees above horizontal. Use the cross cut slide to keep the LS square with the disc and the jig or depressed table to get the correct grinding angle. Before starting be sure the face of the LS is perfectly flat with the disc.

You can refer to the sketch of the LS I previously posted on this thread if you want to check the angles.

Just touch the LS to the wheel, don't push hard, you only want to remove about one thous each time you touch the disc and you don't want to heat up the metal so that it changes color. Constantly check the dimension till you have the correct length. The difference between what you want to grind off the face will be the same as the difference in overall length. The effect of the angle is negligible. I'd shoot for .8175 - .004 = .8135" . You can always grind more off but you can't add any.

Joe

Information

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[Peter Laidler]

We used what we called 'three corner stones' to stone down shoulders and the like. Not too difficult and once you get going it doesn't take too long. I have done countless No4 cocking pieces, sears etc etc including L1A1 locking shoulders. Plus the odd Bren too of course.

We also regularly stoned back the breech block face if it contacted the barrel while checking CHS.

I'm not sure that you can use an unmodified .303 breech block because the 762x54R has a slightly larger base rim diameter and won't fit into the cart seating.

[Vincent]

Ah! I forgot about the larger rim.

[Peter Laidler]

Aside a bit DJ and your comment on brass v steel case. Then yes, steel IS stronger than brass as a material BUT we are talking about steel v brass in an APPLICATION of a metal. I usually follow up with a car related engineering example but can't think of one off hand except to say that brass is FAR more pliable and resilliant. And this is exactly what you need for cartridge cases. It is also a superb method of taking heat out of the gun (easy test for students to test, experiment with and write up.....) although this isn't a feature in this instance.

[jmoore]

Near as I can reference without getting to exact specific alloys, the mild steel used to make cartridge cases has pretty much the same yield and ultimate tensile strengths as cartridge brass. If the steel wasn't of very mild alloy, it would not take the deep draws required to form the finished cases.

[Joe H]

Near as I can reference without getting to exact specific alloys, the mild steel used to make cartridge cases has pretty much the same yield and ultimate tensile strengths as cartridge brass. If the steel wasn't of very mild alloy, it would not take the deep draws required to form the finished cases.

I think a brass case is actually hardened and stronger as a result of cold hardening when the case is formed. The case neck is always annealed (heated and left to cool) so it is softened and will not split. This is the discoloration you see on the case necks of military ammo. Commercial manufacturers usually polish after annealing so you never see the discoloration. The case head is left hard and should never be annealed.

Joe

[Vincent]

The case neck is always annealed (heated and left to cool) so it is softened and will not split.

And it helps the case obturate when the round is fired.

[browningautorifle]

I never thought of steel as better or stronger than brass for cartridges. I always viewed it as a poor second or substitute. It's not really steel anywayzzz...it'll be a softer mixture.

[Peter Laidler]

That's a very valid point BAR. On the same track, then surely if steel was as good as brass, we'd ALL be using it. But it's not. As you say, a reasonable good substitute.

I say that DJ ought to at least try a mag full of brass cased stuff, even if it is to eliminate the steel case proble.

Incidentally DJ, did any of the successfully fired steel cases show signs of belling outwards at the unsupported extractor way part?

[djandj]

That's a very valid point BAR. On the same track, then surely if steel was as good as brass, we'd ALL be using it. But it's not. As you say, a reasonable good substitute.

I say that DJ ought to at least try a mag full of brass cased stuff, even if it is to eliminate the steel case proble.

Incidentally DJ, did any of the successfully fired steel cases show signs of belling outwards at the unsupported extractor way part?

Thanks Peter. As far as the casings go, when things go well, they go very well. NO signs of bulging or undue wear of any sort. (until things DON'T go so well) That's the maddening thing. If the steel weren't good enough, then ALL (or most) of them would fail. One in 60 or so is a different story. As for using brass, that is another option. I saw a sale on Yugo brass surplus 54R for about .33 each. I could do that. Of course, it still defeats the purpose of having the bloody thing built to shoot Soviet 54R surplus to begin with. Furthermore, IF the rifle is firing out of battery as we suspect, merely changing to brass won't solve the problem. But point well taken, it WOULD eliminate the ammo from the equation as a factor.