I have reloaded for years and never even heard of concentricity. Not even sure if I am spelling it right. Anyhow several of the guys at the club talked me into getting a gauge and checking my loaded ammo. Well I wish I hadn't done it. I like good groups but I am not a bench rest shooter nor a millwright so this is a bit over board for me. However having said that I did a little test with a .243 die that looked like the decapping stem was a bit bent. I have heard guys talk about not using the expander plug to help with concentricity. So I took a brand new case and checked it. It was close right about .001 then I ran it thru the die with the expander plug and it went out about .004 -.005. Then I took the expander plug off and resized it again. Back to only .001 and the neck is plenty tight enough to seat a bullet.

Now if I understand this right taking my expander plug off was all I needed to do to bring my concentricity in. Am I right? Should I continue this test with other calibers I load for?

Until you toss a fired case into the mix.

Then the play in your die can come into play as well as the shape and play in your chamber.

For a hunting rifle I've never worried about it.

Donald
If you have a nice smooth table top you can learn to see .003 run out by rolling the ammo across the table and watch the bullet wobble.

If your accuracy is not up to par, roll your ammo across a table. If the wobble is bad fix it.
If there is no wobble there is another problem.

I probably have about as much reloading gadgetry as anyone but I spent a few years running a lathe where concentricity is a big deal. The only time I have had to deal with it was a crooked/bent seating die.

SR, Personally I feel my loads are pretty good for the rifles I have. Most all of my scoped rifles will shoot at least 3 shots into one inch many will put 5 under an inch. A couple will put them in 1/2 inch. However like most I am always trying to do better. My one shooting buddy swears if he shoots his ammo grouped by how far out the concentricity is he gets better groups. Personally for shooting at the club out to 300 yards and for hunting out to 400-500 yards I don't think that gauge is going to help me much. For that I think trigger time is the most important. But being I have the gauge I figure I might as well try and learn how to get as close as I can.

You can go ahead and use it but at the accuracy levels you are achieving you are not likely to find magic in any one solution.

If you are interested in accuracy you might attend a benchrest shoot and talk to some of the shooters and look at their groups.
Their loading methods are very simple. You might like the Wilson neck and seater dies.
A lot of the BR shooters advantages come from brass preparation and a chamber designed for accuracy.

I have 2 old 6X47 Rem. 40X rifles. There is a clear difference between their accuracy capabilities and any other rifles that I have ever owned.

I figure for my needs and wants I am doing fine with factory rifles that have tweeks such as bedding jobs and trigger work. I think I have reached the level I will stay at.

The proof of the pie is in the eating. If you're getting good groups then what else do you need? I made the mistake of buying a concentricy gauge. Spent $100. It told me what I already knew. My ammo was straight. It sits on the shelf gathering dust.
There is always someone with yet another gadget that is gonna give you a short cut to the promise land of one hole groups.
Most folks, if they'd spend more trigger time and less time dicking around in the shop would find their ammo getting better and better.

quote:

Most folks, if they'd spend more trigger time and less time dicking around in the shop would find their ammo getting better and better.

+1