LC LR Brass initial bump?

[fpchief]

Gents,
Quick question. I have acquired 1000's of once fired LC LR brass. Fired from M14's only. I have an Ar-10 and a bolt gun i will be shooting it with. I am sorta confused about the whole shoulder bump. I have a WFT and having big differences in case length after trimming and realized i am not gettin any bump after a FL size with RCBS small base dies. I have NOT shot any of this brass yet.

So....should I get some fired brass from my weapons, use those measurements to set up what i bump the LC brass to? I plan on bumping back .003-.004 so i am good to go with both rifles. I do not want to be concerned about keep rounds separate.

Thanks in advance for any wisdom.

[hounddawg]

shoulder bump has nothing to do with case trimming, even on trimmers that index on the shoulder. Taking .002 off a case whether measuring from the shoulder or measuring from the base is still .002 off regardless of where that .002 is measured from. Measure from the beginning the middle or the end, same result

Now try and convince some guy with several hundred dollars worth of Giraud trimmers of that. Like trying to teach a pig to sing

[Dufus]

If you are shootin' M14 and AR 10, I wouldn't worry about shoulder formation and just full resize. Problems solved.

[fpchief]

10-4 on both replies and I appreciate it. Then what would be causing cases to be slow to chamber and hard to extract? Talking about empty but sized cases...

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[USSR]

Since one of your rifles is a bolt gun, here is what I would do. With your resizing die set up so that it is just a hair above the case holder, resize a LC LR case and see if it chambers in the bolt gun - probably not. Then, screw the die in a little further and try again. Keep doing this, and at some point the shoulder will be bumped back enough that your bolt will close on the case. Lock it in place there. Chances are the AR-10 chamber will not be smaller than the bolt gun's chamber and you will be GTG for both. Hope that helps.

Don

[jpx2rk]

Since you have "1000's" of them, I would sort or divide the cases into those for the AR and those for the bolt gun, and keep them separate going forward, will make like easier since the chambers will probably be different sizes. Semi's need a bit more "bump" than bolt action rifles. JMO

[std7mag]

I'm confused...
By "M14" do you mean Ruger Mini 14?
Or the military designation for the M1A?

Huge difference on cartridges there!

I'm sure this topic has been discussed in quite some depth.

[USSR]

I'm confused...
By "M14" do you mean Ruger Mini 14?
Or the military designation for the M1A?

Since LC LR is USGI sniper ammo, is only made in 7.62x51, and is once-fired, he is talking about a USGI M14.

Don

[fpchief]

Originally Posted by USSR

Since one of your rifles is a bolt gun, here is what I would do. With your resizing die set up so that it is just a hair above the case holder, resize a LC LR case and see if it chambers in the bolt gun - probably not. Then, screw the die in a little further and try again. Keep doing this, and at some point the shoulder will be bumped back enough that your bolt will close on the case. Lock it in place there. Chances are the AR-10 chamber will not be smaller than the bolt gun's chamber and you will be GTG for both. Hope that helps.

Don

Thank you. Will work on that tonight.

Kip

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[fpchief]

Originally Posted by jpx2rk

Since you have "1000's" of them, I would sort or divide the cases into those for the AR and those for the bolt gun, and keep them separate going forward, will make like easier since the chambers will probably be different sizes. Semi's need a bit more "bump" than bolt action rifles. JMO

Great idea and I appreciate the opinion...my deal is I do not want to have to separate ammo for individual rifles. Causes problems in a crisis.

Kip

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[Unclenick]

Fpchief,

We just recently had a thread in which a member was failing to get the shoulders of his cases to come out where he wanted them. It turned out he was unaware that resizing force stretches a standard loading press, so the mouth of his sizing die was actually losing contact with the deck of the shell holder during resizing and his cases were coming out that much too long. What you want to do is what happens at the end of this Lee Help Video, where the fellow looks sideways to make sure there is no crack of light between the mouth of the sizing die and the deck of the shell holder. If there is, the die needs to be turned in further.

If you have already done that and your case shoulders are still short, check that they are no longer than 1.630" from the head to where the shoulder diameter is 0.400" (the shoulder datum location). The easiest way to do this is to use any brand case comparator and use it to measure a 308 Winchester chamber GO gauge and just make sure your cases are at least equally short or a little shorter for AR feeding.

If your cases are still long, remove the decapping pin and slip a feeler gauge into the shell holder under a case to raise it, and then resize again. It will be resized shorter by the thickness of the feeler gauge.

If you are still having issues due to these cases being fired in very long chambers, then see if you can load them with some cheap bullets (147-grain M80 or European surplus ball pull-down bullets are fine) and a starting load of your powder of choice and firing them in the bolt gun, assuming you can force the bolt closed on them. That should get all the cases about the same size. Then resize separately for the bolt gun and the AR, as mentioned before.

[hounddawg]

It turned out he was unaware that resizing force stretches a standard loading press, so the mouth of his sizing die was actually losing contact with the deck of the shell holder during resizing and his cases were coming out that much too long.

for many years I have been wondering why I needed to go further than the initial contact and then double bump when resizing, now I know why. Thanks UncleNick. Love this forum