Concentricity??

[Kansaswoodguy]

I have two concentricity gauges one I bought new, one that came with a bunch of reloading equipment I acquired from a guy that was getting out of reloading. I don't use either very much. I will say if you play around with them and your dies you can usually tune your dies for low concentricity readings. Now whether low concentricity readings equate to more accuracy is debatable I'm not sure it matters that much. I fooled around with it when diving deep down the reloading rabbit hole I've since crawled back out of that hole back to reality.

 

[Jack300WSM]

that rabbit 🕳 has a lot of hopes & money in it for sure.

 

[Jeff Heeg osoh]

Just want to mention take your favorite factory ammo that shoots lights out accurate and measure the run out, it will surprise you how much it has. Checking your brass just below the shoulder after sizing give you and idea of the quality of the sizing die, then comparing it when loaded at the bearing surface of the bullet gives reference to seating as well. Also seeing what the chamber does to the brass after fired at the shoulder area again - some chambers that were cut sloppy will give the case a slight banana shape.

Bottom line is that accurate factory load that shoot lights out and surprisingly the amount of run out you will find - you will think you are a expert on your reloads then.

osoh

 

[Wolf76]

Runout is on the list of important things, it just isn't in the top 5. Its one of the fine tune adjustments.
If powder charge and seating depth aren't optimized, runout will make nearly zero difference.

 

[30BR]

Went down that rabbit hole a few years ago with that tool with my match ammo. fiddled until all rounds were within .002" of runout.

It made absolutely no difference whatsoever in my groups so I never did it again.

 

[lancetkenyon]

Below is my procedure for checking runout:
1. Buy quality dies
2. Buy quality components
3.
4.

 

[whirlwindjml]

I Check run out on the target.

 

[Mike Matteson]

I got a concentric Hornady tool. Never had one until last year. I did some checking on my reloads, Most were about dead on. I have been reloading for 63 yrs by that time. I have always been very careful about placing my bullets into the case, making use they are straight going in to seat the bullets. to boot I use an RCBS standard seating die. Once dial in on loads, my group are generally about 1/2" @ 100yds. I do cut my necks for thickness for 20+ yrs. I do feel that if the bullet is not straight in the case it will create a problem for you. Somebody with more knowledge than me, can show what's really going on.

 

[Rob L.]

Couple questions here...
1) Is the .004" runout TIR on that indicator? (Total indicator reading?) If so, then that's only .002" out of center.
2) When checking the runout at the bullet, have you checked the runout at the base? In other words, is the base bang on and only the tip runs out? Or are both locations out?

 

[Hairtrigger]

Just for fun, you should check factory ammo.

I have used a concentricity gauge as a troubleshooting tool trying to find out why something would not shoot up to my expectations. I have never used a concentricity gauge as a way of looking for trouble

 

[QuietTexan]

Measuring a loaded round with tool on bullet ogive is what I was doing. I turn necks but hadn't thought about checking them

0.004" on the ogive with that tool, I wouldn't worry for a second.

Rob brought up a good point, though. I assumed this was total indicated, which I why I threw out 0.010" (or 0.005" out of center) as the point to worry about. I'd be surprised if you're seeing 0.008" total using a mandrel and FL die combo, the tools you listed are quality enough that runout shouldn't be a problem for you.

I have an EC Tuner brake at like it a lot, quality little bit of machine work.

 

[Jack300WSM]

Didn't look at it that way either. Yes, .004" overall so it's half of that if I'm thinking correctly. So yeah .010" would appear to be pretty y by that rationale anyway. Like many have said I guess I'll just have to shoot those rounds that come out on the high end and compare results. All good info and appreciate all the input sorting through this

 

[Mikecr]

If 4thou eccentricity on a 'Hornady Concentricity Guage', then your actual runout is a lot higher still.
It's getting up there

 

[Dragoon300]

I use the Hornady concentricity gage on every precision rifle load I do. If there is a load with over .001 TIR concentricity I adjust it in with the gage to less than .001 run out.
If the brass necks too hard they spring back too much for this feature to work easily. So annealing is neccessary.
I found the biggest factor contributing to concentricity problems is the sizing ball in the die pulling the neck out if dry. I now mandrel size the necks. Concentricity is just another variable to deal with in the quest for more precision, and this tool works very well for me.