How much force needed to set back a .308 bullet?

JimGnitecki

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If you hand load a .308 round (175g Sieraa Matchking), for sue in an autoloader, you want to ensure that neither recoil nor feeding will set back the bullet.

I've been told by more than one source that an interference fit of .003" between the bullet and the case is sufficient.

But, to quality check a batch of rounds, you would check to see how much force is needed to set back the bullet if you apply the force to the tip of the bullet, while the base of the case is against a rigid support, right? (like on a K&M Arbor with force measuring kit).

How much force should it take to set back the bullet?

Jim G
 

Fuzzball

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Re: How much force needed to set back a .308 bullet?

"I've been told by more than one source that an interference fit of .003" between the bullet and the case is sufficient."

That's pretty much the target most die makers try to achieve but one thou of interference is actually about all that matters. More than that just stretches the brass passed it's elastic limit and deforms the neck until only 1-1.5 thou of elasticity is left.

I've never heard of anyone trying to qualify how much force seating takes but it's certainly harder to push a bullet into a small neck than a proper sized one. Any such figure would be meaningless anyway, there's too much variation in presses, bullet alloy friction coefficent and inner neck surfaces to make it useful.
 

turbo54

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Re: How much force needed to set back a .308 bullet?

Right on point again, Fuzzball. Great post. Open/shut case.
 

Nessal

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Re: How much force needed to set back a .308 bullet?

If you need a crimper to get the proper neck tension then you got other problems to worry about.
 

JimGnitecki

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Re: How much force needed to set back a .308 bullet?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Nessal</div><div class="ubbcode-body">If you need a crimper to get the proper neck tension then you got other problems to worry about. </div></div>

I agree that crimping s not desirable. Very detrimental effect on accuracy.

Jim G
 

Fuzzball

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Re: How much force needed to set back a .308 bullet?

"I agree that crimping s not desirable. Very detrimental effect on accuracy."

I agree that massively over-done crimping is detrimental to accuracy, and that is the way a LOT of crimping gets done.
 

5R Milspec

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Re: How much force needed to set back a .308 bullet?

sorry for the post on crimping the bullet.but he did say he was loading for an auto loading rifel.for me I too wouldn't be worried about the bullet being set back.I would be worried about the bullet being pulled out into the lands and not fireing the round.then he will have a mess to deal with.

well I have been there and done that before in a bolt action.ran another round in hard and fast.then not fire it.found it hard to remove the round whole pulling the bullet out without knowing.well you know the rest.

I don't think with the new and better auto loading rifels you will have anything to worry about.the gas systems on the newer rifels are better than ever.its that when you feed or the rifel feeds a loaded round that hasn't been crimped can and will cause you pain.