Bottleneck Case Not Concentric

In some cases chambering them can reduce or eliminate runout.

It can make a difference but there are lots of folks/firearms that couldn’t tell a “good” round from a “bad” one.

A drill is not the best tool to be checking them with. The holder may be causing some issue too.

If it's once fired out of your gun, you will need to have your action trued. If the gun has not been trued the only way would be to shoot new brass. Now if your not shooting past 300-500 yrds it may not make any difference.

A drill isn’t even a decent tool to use for testing run out, let alone “not the best.”

Keyfer 55 said:

What effect does non cconcentric have on accuraticy. When I rotate onec fireed case in drill I see there not concentric should I scrap them ???

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While I agree rotating a case in a drill is not the best way to check how concentric a case is because you really don't get any real numbers another question is how did it get that way? Did it go in concentric and come out non-concentric? There are tools made and some great home brew tools for actually checking if a case is concentric which give you real world numbers. You may want to look at some of them. Member jmorris above has posted some pretty cool home brew stuff.

Ron

“How much” is the key and as others mentioned a tapered case in a chuck isn’t ideal at all. Letting it roll on a table may actually be better.

I have made some simple tools that put values to things that are not true.

This one is very easy to use but is limited in the information it can give you.



This one can tell you much more but isn’t quite as simple.



This might be a little deceiving because for various reasons measurements can differ but you can see even just a slot in a hunk of metal and an indicator can give you at least repeatable numbers on the same round.

Keyfer 55 said:

What effect does non cconcentric have on accuraticy. When I rotate onec fireed case in drill I see there not concentric should I scrap them ???

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Can you elaborate on what you're trying to build (hunting rounds, target rounds for recreation, target rounds for competing, etc.), what your current processes are like (FL sizing? Neck Sizing? Sizing with neck tension bushing? Etc.), and whether or not your current methods are enabling you to achieve what you want given what you're building ammo for?

I've got a calibrated drill

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In that case you should be telling us...

Keyfer 55 said:

I've got a calibrated drill

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What "caliber" is your calibrated drill?

You need to head on over to Sinclair (Brownells) and spend large sums of money.

https://www.sinclairintl.com/guntech/bullet-concentricity-related-issues/detail.htm?lid=16572

One day I will get one of these: http://www.xxicsi.com/concentricity-gauge.html

I reload is for accuraticy.

Well then you should learn how to spell accuracy.

snuffy said:

I reload is for accuraticy.

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Not me. I chase accuracmacy.

ATLDave said:

Not me. I chase accuracmacy.

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Yeah and it can be elusive.

Ron

Keyfer 55 said:

there was a noticeable difference between my brass beside the range brass. The range brass has a wobble.

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I'm trying to come up with a 'visual', but I'm failing miserably...
If all other things are equal, I tend to believe 'a noticeable wobble' would be a factor in how many (or few) I'd attempt to work with.

I’m studying triggernometry, and someday when I grow up I want to become an accuronomer.

You can get a dial indicator that will do the job for around $20 bucks and make a stand for it and get some v blocks for about the same. That's about the cheapest that you will be able to put numbers to your wobble.

Varminterror said:

I’m studying triggernometry, and someday when I grow up I want to become an accuronomer.

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There’s actually a pretty good podcast called Triggernometry. Some Kiwi interviews folks, mostly Americans, from precision rifle shooting fields/companies.

In the meantime, let’s not lose sight of the important distinction between accuramacy and precisitation.

Reloadron said:

Yeah and it can be elusive.

Ron

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And ‘spansive

For the OP - a hint at why we’re being so tongue-and-cheek about your problem: If you have legitimately visible run out, you need to throw away everything you’re currently using.

If you have visible run out in new brass, you have bad brass.

If you have visible run out in sized brass, you have bad dies or a bad press.

If you have visible run out in fired brass, you have a bad rifle (barrel, bolt, or action, hard telling with so little info).

If you just see some out of round case mouths in a bunch of range brass and calling it out of spec, then you’re analyzing something you don’t yet understand. Most gas guns will smash the case mouth of a cartridge upon extraction. Even some of my bolt guns will do so if I run the bolt hard and fast. Brass is soft and malleable, you can fix a great many things about brass in the reloading prep process.

If you’re spinning cases in a drill chuck and calling them egg shaped, your QA program is what’s egg shaped.

I wonder what OP is shooting ? More than a few milsurps have off-center chambers (for lack of a better way to 'splain it).
I know a shooter at the monthly Bolt-gun match that marks his brass in such a way that allows him to 'clock' the brass consistently. I don't know if it helps, but he regularly outshoots me.

Of course, most all of them at the match outshoot me, because I'm not very good.....