Concentricity tolerance

[LeeC]

I'm getting .001 runout on the 204 (.003 on my 6.5). This is the same with just case necks, and loaded rounds. Using Lee fl and n dies. What is acceptable?

[acloco]

0.001" or less is great.

Remove the sizing ball from your dies, I bet the runout decreases a little more.

[LeeC]

Yes it does. Reduced the 204 to almost nil, and the 6.5 to about .0014. Thanks much.

[Over-the-Hill]

acloco, is this a common practice? Taking the expander plug off doesn't create any problems with neck tension or seating the bullet? I'm still very new at this so just inquiring.
Thanks,
OtH

[Rick in Oregon]

Lee: Another method is to leave the expander ball in, but don't lock down the lock ring on the expander stem on the die. This will allow the ball to "self-center" in the case neck. That way, you get the proper neck tension needed (if not using bushing dies), bullets will seat properly, and the TIR will be greatly reduced.

Ideally, TIR should be "zero", but in the real world, this is possible, but not easily obtainable on a routine basis without putting some effort into the process. If you are there now or at .001", you'll notice the difference on paper right away.

[acloco]

Yes. Try a practice case. Size with your normal die but remove the seating ball. Don't primer or powder the case, just try to seat a bullet and check for yourself.

acloco, is this a common practice? Taking the expander plug off doesn't create any problems with neck tension or seating the bullet? I'm still very new at this so just inquiring.
Thanks,
OtH

[Aim4gold]

I have been preparing some remington brass. My last procedure was to run it through my RCBS full length die with the guts removed. Now the runout is ZERO for the most part. Then I use a Redding bushing die to size the necks, now the majority of the runout is 0.003". I have been told that after it has been fired the runout will be reduced when sizing.

I really don't see how, being the neck die induced 0.003", but that is what I have been told.
And yes, I have turned the necks and culled out bad ones and I have the expander installed as per instructions, 1/16 of a turn backed off.

[Rick in Oregon]

I'm wondering why you'd want to overwork your brass by sizing the neck twice. Why would you want to F/L size new brass? If it fits in your chamber when new, you only need to neck size for proper bullet tension.

Measuring new brass for TIR is a waste of time. It is only meaningful if it's been fired in your chamber, or measured after being fired and then reloaded.

You are inducing the .003" TIR by your die adjustment. Never tighten the die in the press unless it is bottomed out on the shellholder or a piece of precision ground steel, as 7/8"-14 threads have much slop, and if tightened prior to being bottomed out, they will never give zero TIR.....ever.

[Bayou City Boy]

I'm wondering why you'd want to overwork your brass by sizing the neck twice. Why would you want to F/L size new brass? If it fits in your chamber when new, you only need to neck size for proper bullet tension.

Measuring new brass for TIR is a waste of time. It is only meaningful if it's been fired in your chamber, or measured after being fired and then reloaded.

You are inducing the .003" TIR by your die adjustment. Never tighten the die in the press unless it is bottomed out on the shellholder or a piece of precision ground steel, as 7/8"-14 threads have much slop, and if tightened prior to being bottomed out, they will never give zero TIR.....ever.

Rick's advice about a piece of precision ground steel to align your shell holder and the bottom of the die before you lock the die in place is about the only way to insure (if the dies are cut properly in the first place) that the die will align properly and not cause run out. I never tighten a die in the press without using a piece of hardened steel that I had cut years ago for exactly that purpose. It is about the size of a 50 cent piece in diameter and 0.375" thick.

Set the die depth location per manufacturer instructions on matching up with the shell holder, drop the shell holder down out of the way with the press handle, and then place the metal piece between the two items and raise the shell holder up to lightly compress the metal piece between the shell holder and die and then tighten the die while the upward pressure is applied.

If you are FL sizing ammo like many folks do for reliable chambering in larger bore hunting rifles, place a rubber O-ring under the lock nut for the expander rod and ball and hand tighten it . This will keep the rod from being floppy (like it is when it is intentionally left loose). The O-ring will allow the expander rod to flex if necessary and still center on the case and it will not increase run out beyond what the die itself is capable of maintaining.

I use O-rings on all FL dies, irregardless of caliber. I normally neck size only, but occasionally you have to slightly bump the shoulder on cases for easy chambering after a few firings. Having the expander rod in place with an O-ring under the nut will not distort the brass and cause excessive run out.

-BCB

[remy3424]

Nice lesson taught on this thread, thanks for those live and learn tips!!! Can't wait to try it!! New to me, but maybe everyone except me....and "over-the-hill knew this one!!! Thanks again.

[Aim4gold]

[quote="Rick in Oregon"]
Measuring new brass for TIR is a waste of time. It is only meaningful if it's been fired in your chamber, or measured after being fired and then reloaded.
quote]

When working up a load on a "new rifle" with "new brass" - I always check runout and sort, using the >.001" runout for load work up.