request: advice for best concentricity

[Rick in Oregon]

bow: It's a waste of time to measure TIR on any new brass prior to having been fired and/or sized.

Also, personally, I'd never seat a bullet into new brass that had not been either F/L or neck sized.....never. You'll get the worst TIR readings you've ever seen.

[bow shot]

Original quote was:

I took some measurements of the TIR of the unfired brass, the necked brass and TIR of the seated bullets.

should have been:

I took some measurements of the TIR of the 1x FIRED brass, again after necked sizing, and then TIR of the seated bullets (in the 1x fired, neck sized brass).

[Rick in Oregon]

[bow shot]

....Sorry for the confusion.

[jo191145]

bowshot

Been following this post. Gotta say I'm happy I never bought a concenticity guage now:lol:
Seems to me just by memory over the years folks who take the time to do all this measuring usually end up with a Redding seater.
I think it was "Skipper" who first posted about .006" runout with the Forster.
Don't take my word on any of that. I'm still using a standard RCBS seater which doubtfully rates very high on the quality list.

Your shrinking brass is common and to be expected. Virgin brass must be sized to fit any chamber produced. Upon fireforming it must expand to fill your chamber. While the body of the case will stretch also, the greatest amount of brass is drawn backwards from the neck area. The neck area is annealed from the factory equaling softer brass which flows easier.

[bow shot]

Yes, I'm getting to the point where, given the class of my weapon and my shooting/loading skill level, I perceive that chasing this run out thing is self-induced agony that would likely only benefit shooters/loaders of a finer breed.

'But I'll go as far as I'm able with the resources that I have, which are pretty patchy, and learn as much as I can.

Thanks for the confirmation on the shrinking brass phenomenon, that one threw me a bit.

At this point is seems that I'll have to neck turn the brass, and/or buy a Redding or Wilson seater. A friend has a Forster turner that I can borrow, I just have to get a 20 cal pilot for that.

So I think the next thing to try is to uniform (turn) some necks, seat 'em with the Forster die, and see if there is some improvement in the TIR at the bullet (the sample will have to be made of members all having close to 0" neck wall thickness variation and TIR). If it bullet runout is still poor at that point, I'll likely pray for a Redding or Wilson seater to fall down from the sky.

[jo191145]

Don't get me wrong. I'm not opposed to loading straight ammo
My factory and custom rifles will shoot pretty good without checking runout so I never felt it was a problem I needed to address. Surely can't hurt tho.
I do use O-rings in the few sizers I still have with expander balls present. I've squared the top of my ram to the die threads as best I can with the tools I have. I even removed the shellholder retaining clip from the ram as I read this can cause runout. Takes a while to get used to using shellholders that are not held in place.
Obviously I have no idea if any of this has helped or hurt.

All your measurements seem normal until seating the bullet. Seems logical the problem lies somewhere in that area. Not necessarily the seaters fault either. I would imagine unsquare case mouths, unsymmetrical chamfers and excess neck tension could play a role too.

Don't forget to retest your $10 Lee seater too. Who knows ? Just might be better.

[bow shot]

jo191145, agreed on all points.

'Lots of variables here... I have been noticing as I search around that the die/shellholder/ram interface can be a touchy issue as you've said. I think it requires investigation, because my other ducks seem to be lined up. And the bullet TIRs on the last batch have not regularly equated to the brass variables. Ie., I've had instances (with this last batch) where the brass TIR was under 0.001", the neck wall thickness delta was under 0.001", but the runout for the bullet once seated was at the high end. I've had it work the other way around also. 'don't have the data on hand..

I'm aware that I may find out that once I've developed the skill to mfg perfctly straight ammo, that it was a non-issue after all (for this gun, this round, this shooter, etc..). On the other hand, it may be huge..

[bpratl]

agreed on all points.'Lots of variables here... I have been noticing as I search around that the die/shellholder/ram interface can be a touchy issue as you've said. I think it requires investigation, because my other ducks seem to be lined up.
huge..

That's for sure. I know that it is a lot of work, and expensive, in chasing run out but; I personally enjoy it and I find it very rewarding when I minimize it. I try to rule out all the variables so when I squeeze the trigger I know it is me when I don't get clover leafs or bug holes.

[bow shot]

precisely!

[bow shot]

Here are the numbers..

1) Nosler brass TIR after firing for the first time in the Savage VLP:
36 @ 0 - 0.0015"
5 @ 0.002"
3 @ 0.003"
4 @ 0.004"
2 @ 0.005"

2) After neck sizing (Lee Collet die): Almost every TIR number reduced by 0.001"

3) 40 gr VMax bullet TIR (short of the olgive) after seating (Forster BR die):
5@ 0.001"
6 @ 0.002"
12 @ 0.003"
10 @ 0.004"
8@ 0.005"
7 @ 0.006"
2 @ 0.007"

'Of note:
1) All figures are rounded
2) Again, after neck sizing (Lee Collet die) most TIR numbers reduced by 0.001", the two highest figures actually reduced a lot, by .003" and .002". I'm thinking these were dinged during ejection from the action and the mandrel of the collet sizer fixed that. This may be true for every round to a lesser degree...
3) I didn't clean the ID of the necks.
4) After all operations were finished, I took my collet sizer apart for cleaning, and it was pretty filthy...

[Rick in Oregon]

bow: Remember that if these measurements are taken from domestic factory brass that has not been neck turned, you're bound to get numbers in this range, it's just "the way of the world" in factory chambers using domestic brass.

After brass passes through an expander ball, any neck thickness variation is then transferred to the outside of the neck. When you measure your brass TIR, just keep that in mind.

You may be making too much of this TIR thing....if you're loaded rounds are less than .002" TIR, ideally less of course, well then it's time to go shoot some varmints! Spring is right around the corner................

[bow shot]

Understood, Rick. I'm pretty much continuing this as a learning experience.

My path from here will likely be:

1) Borrow my friend's Forster turner, uniform the necks on a batch of 20, and see what that gets me (for straight ammo).
2) Research squaring the ram/shell holder/die interface (I see the O-ring idea lately)...again see what that gets me (for straight ammo).
3) Just move on with life, straight ammo or no.

I think at this stage I'm moving along and posting so that mothers can tell their sons not to do the things I've done.

[bow shot]

This is just an FYI, maybe it will help someone someday? This is in no way a commentary on the quality of the brass, dies, etc. This is just variable data on which to ruminate.

I was a bit bummed after the last seating job (Nosler brass, Forster seater) and wondered if I did something wrong (other than that, as the present wisdom indicates, I probably should fire the brass more before expecting good bullet run out results) .

I had some time last Saturday, so I experimented a bit:

1) Pulled all 50 bullets with an inertia puller. Generally took one solid whack, and then one light whack.

2) Re-measured neck wall thickness to (and confirmed initial measurements):
46 @ 0.000 - 0.001",
4 @ a tad over up to 0.0015".

3) Re-neck sized (Lee collet) everything and measured brass TIR:
The majority fell in the 0.001 - 0.002" range, but a few (5?) were pretty far out at about 0.004". I was able to bring these down to 0.002" by rotating the shell holder 'round the clock in 12 increments, pressing into the sizer at each increment.

4) Seated 10 bullets again w/Forster seater: Same results as initial seating. Rats, they ranged from 0.001” to 0.006” TIR, more to the high side than the low.

Of interest:
1) I could not get bullet TIR to correlate to… well, anything except to seating. I repeated steps 1-4 several times, using the impact puller, re-neck- sizing, and re-seating (w/ no powder in the brass) and got varying results. Brass with the best neck wall and TIR sometimes often gave me the worst bullet run out. It worked the other way too. I did go through pains to align the bullet by eye as best as possible before raising the assembly into the seater die. I only chamfered enough to clean the soot off the brass (these come chamfered from Nosler) , and the bullets are boat tailed, so they made with the brass very justly before seating.

2) If I seated deeper, it was more difficult to get good bullet TIR

3) With the cartridge supported in a v-block, it was fairly easy to bear on the tip of a bullet with bad (0.005, 0.006") TIR and get it to register 0.001" TIR. Often, I could actually feel a slight "click" of sorts when the bullet "homed". Makes me wonder what happens to neck tension….

4) I’m open to the fact that I could be doing something wrong, and that it may take another firing or two for run out to tame down the run out…

[Ray P]

bow shot...............I try my .02........You made a comment that when you seat bullets deep in the case its hard to get a good reading. Your indicator should be running on the bearing surface of the bullet and not the tip! Some bullet ojves will drive you crazy tring to measure TIR out at the tip. If this were your tring to take a reading.
Hope this helps little.
Later
Ray P