Concentricity & Runout Correction

[22~308TargetShooter]

Ok, Long time Competitive Smallbore shooter, but I'm fairly new to Mid Range, Long Range, and Palma Competition as far as the reloading aspect of the game goes and only been reloading now for about a year for my .308 and those tournaments. I'm trying to pull out all the stops on precision and turning out consistant rounds. I do everything by hand , no case prep centers with power tools or anything. I know it takes longer but I enjoy the process. This season I've taken my process now into considering concentricity. I'm using the Sinclair Conc. Gauge, and I realized that some of the others had an advertised correction feature, but still went with the Sinclair. What I'm wondering is if anyone out there not using one with the feature to tip the bullet slightly, how do you attempt the slight correction, or do you attempt it at all, and if it's too far out of your acceptable range does that round just become a fouler or sighter ? I've been able to with a little slight pressure between my thumb and forefinger make a slight adjustment to the bullet if needed, and I can on average get my runout down to .001 or there abouts. My other concern is how much does anyone feel this alters neck tension adversely ? ???

C.D.

 

[fdshuster]

C.D.: There has been a lot of discussion here about this very topic. Especially so after Hornady brought their runout & straightening tool on the market about 2 years ago. I bought one when they first became available, did not like it & it was sold.

I've been using the Sinclair tool for about 7 years, also had the RCBS at the same time & was able to compare them side-by-side. Prefer the Sinclair & kept that one.

The vast majority of my runout problems can be attributed to an occassional piece of defective, sub-standard brass. And, yes, I'm also including Lapua in that statement, the brand I use the most of.

Of a box of 20 rounds, I may have 1 or 2 that will have a loaded round runout of .002" to .004". The rest will be well under .002", most of those .001" or no visable runout at all. These "bad" cases are marked with a black magic market, on the case head, and with repeat loadings will always continue to have the same runout. The remainder will continue to be excellent. To me, proof that it's defective brass, from the time it was formed. Otherwise, if it were any other cause all 20 would have runout.

As you said, the "bad" brass is kept for basic scope sight-in, first round foulers, and limited to 100 yds/ mtrs., avoiding their use in match's. But, surprisingly I've gotten some very excellent 5 shot groups at the closer distances with the "bad" brass, comparable to "good" brass, but do believe it could be a problem at the longer distances, 300 & beyond.

No, I do not believe in attempting to straighten them, although I realize others report great success.

 

[DennisH]

Any loads .004 and less . . . I drilled a hole in an oak board for my 308. If it's out .004 or less, I just put it in the hole and apply a little pressure. I usually get to .001 of less with no problem.

If the runout is + .004, I usually put it to the side! I just DON'T know what's giving when I correct one with more than .004 runout!

I have had some Lapua in from the same box that was .008 out! They say try an inside reamer, but since there only a few, I use them for sighters!

I use Forster, RCBS Gold Medal Comp dies, and Redding dies, I find these are the best!

 

[mikecr]

I agree with fdshuster
Focus on the causes of runout instead of fixing the end result.

For those wild ones departing from the pack, the cause is thickness variance, and in this regard Lapua is not really better than other brands.
You can cull these out before any other preps using a neck mic.

 

[necchi]

Good question and good answers.
I'm all for trying to find out where the run out is happening and tuning your technique.
I've found if you have a straight case neck, most of it is the actual act of seating.

Starting straight is a plus, then seating in 3-4 short strokes turning the case in the shell holder a little each time.

I do like yourself and will thumb them over if they're just a little out to be successfull.

I've done like Dennis and stuck the bullet in a pre-drilled hole, or use a fired case with an open neck and use it to apply more pressure than the thumb,,
,,not so successfull.

If I have to move it more than .001-.002 I beleive it stresses the case neck and the round is lost to anything but practice,, they just don't land in a happy place for a good group

 

[BoydAllen]

What dies do you use, what brands of brass in what calibers; do you turn necks, and are your chambers factory, or custom with close, or tight necks?

 

[DennisH]

If I have to move it more than .001-.002 I beleive it stresses the case neck and the round is lost to anything but practice,, they just don't land in a happy place for a good group

This is what I was wondering! What actually gives? Several members straighten there bullets out like I do but I really don't know if this is good for the brass or bullet, or for that matter, the barrel!

So what do you do, the ones that initially measure .002 or less, just keep them seperate? OR?

 

[Shynloco]

Guys,
Let me play devil's advocate for a second and ask a question since I believe there is alot of validity in what has been said. Say your concentricity (runout) exceeds the .001-.002 limits that we seem to all have settled on in terms of an acceptible runout error. And I'm not talking .006 out here. For those who have made "the correction," whatever the method used, how has you target or grouping changed because of having had to make the correction? I'm hearing a concern over the neck tension which I've become acutely aware and concerned about. If that concern is valid, what was the end result for the corrected error? Just asking for what you guys have found. And I also segregate out any brass that is well outside the correctible parameters and use it for foulers. Thx!

Alex

 

[BoydAllen]

I think that internet accounts of what has been done and what the results have been need a lot of background information to be worth anything.

IMO the differences that might result from correcting a loaded rounds slight deviations from straightness, as so subtile as to require a really well tuned system, that is properly operated to be seen. Furthermore, if the best brass, dies, and loading procedure are used, this becomes an even more difficult task.

Before you start off on this determination, I think that you should ask yourself what the AVERAGE performance of the system that you are using as a measuring tool is, not what its best wallet group is, but the average. Lacking something that can turn in reliable quarter inch groups, I wold say that one does not have the proper equipment for the task. It would be like comparing the thickness of dimes by measuring them with a Crecent wrench.

 

[mikecr]

Whoa,, WHOA now! Crescent wrenches work for -stuff