Home Forums Hunting & Shooting Ask The Gunwriters Question for J.B.

Good morning John. What I need to know about are concentricity gauges. I really don't know anything about them or how they will up my game, but I have a hankerin' to get myself one and tinker with it.
Does it measure loaded rounds or fired cases? Is it worth spending $150.00 on one? Being an accuracy nut and a rifle loony, I just can't help but to find things that might tighten my groups. By the way, I am in the process of reading Gun Gack 2. Very informative and well written.

I'm not JB but I may be able to help fill you in.

I use a Sinclair gauge. It can measure straightness of loaded cartridges and empty brass, and it is a good diagnostic tool. Making checks at each stage of the handloading process will find where runout is coming in. Once the sources of runout are eliminated then it becomes a quality control tool.

From an old post of mine:

+1 Sinclair gauge.

Straighten with TruAngle tool.

DF

Thanks for the feedback guys. DF, what is a TruAngle tool, how much does it cost, and how do you use it? Thanks in advance.

http://www.trutool-equipment.com/TruAngle%20Guide.pdf

I mounted mine on a board.

DF

Another 2 cents.
John B has written several good articles about concentricity, where the problems come from, simple checks, and reviews of several of the tools to test for it. You are liable to get a better understanding reading those than he'll be able to provide here.
Further, in my experience, that if you start with very good brass, and reliably good tooling (dies and press), you are well on your way to avoiding the problem. Avoiding is way better than fixing.
Might be interesting to note, that back in the 50's and 60's, when the American Rifleman was far more of a technical publications, this issue was discussed in several times.
mathman's recommendation is worthy of your consideration.

jackhammer,

Fishdog is correct. I've written quite about all this, more than can be condensed into a paragraph or two here. Much of it I collected and updated in THE BIG BOOK OF GUN GACK, available from www.riflesandrecipes.com.

However, I will note that while owning several concentricity gauges, the one I end up using the most is the RCBS Casemaster, because it also features a handy way to measure case-neck thickness.

Mule Deer,
Read volume 1 and 2 in recent weeks, but could not remember which volume this was written up. Sadly, both copies have been lent out. I should have anticipated that an bought a six pack of them. Would have gone a long ways toward filling some upcoming birthday gifts. Truly good stuff.
Further, I am delighted that you are continue to respond without cursing, personal attacks and funky grammar. I treasure civil thoughtfulness. It benefits the entire Campfire.
Thank you.

I have nothing to add other than the fact that mathman is the man. I forget what the name of the thread that he is referring to, but his comments were so helpful and beneficial to my reloading, that I printed them off and refer to them frequently.

And since I am commenting I will ask another question. I manage to keep runout to 2-3 thousand through all the steps, measuring it between all the steps. My problem occurs when seating the bullet. Runout will climb to 6-9 thousand. I am using a single stage RCBS and the forster bench rest seating die. I am reloading for the 280 with 140 grain Nosler Accubonds. Other than the die not liking those particular bullets, can you think of anything else causing that?

Thanks

John, I own both Gun Gack books. Guess I'll read up on run out in Vol. 1. Thanks everybody for the info.

What are "all the steps" that you are measuring 2-3 thousandths of run-out? Personally, that amount seems way too high for anything other than a seated bullet. I've found that my final run-out is roughly 2-3x the neck run-out before the bullet is seated. I like to see 0.001 or less neck run-out before seating a bullet, but will often "try" a case that has between 0.0015" and 0.002" neck run-out. Anything above 0.002" neck run-out automatically gets culled for fouling shots or out-right discarded. And I personally do not feel I have super high accuracy standards (my loads are for hunting, not competition).

It wouldn't surprise me if a case had 0.003" neck run-out to turn into 0.006-0.009" total run-out.

jackhammer,

There's info in Chapter 1, "Working Up Loads in the 21st Century," and Chapter 6, "Sizing Cases Straight." I just submitted another article to HANDLOADER about rifle-die design that will contain a little new info I just came up with.

fishdog,

Thanks for the comments, but I don't always entirely maintain my civility here!

who is selling the tru angle tool ?

Ed

Just read chapter 6. I now have another couple of questions. I use Redding type s neck sizing dies and regular redding or RCBS seating dies for almost everything.That said, I find that when using Lapua brass in my RCBS Rockchucker press that even when using an RCBS #11 shellholder I sometimes can't get the brass all the way into the shellholder, and I know that the cases are sized and the bullets are seated crooked because of this.
This morning I ordered a Redding "E-Z feed" #1 shellholder to hopefully correct this problem. Now keeping in mind I am an accuracy nut, (not to the point of turning necks, but I will ream the inside of the necks using a case trimmer) do you think that the shellholder will work, and also will owning a concentricity gauge, a TruAngle tool, and culling brass turn 1" groups into 1/2" groups? Thanks in advance.

The best I can answer is "maybe." It depends on bullet and rifle quality, and obviously shooter skill.

I've written quite a bit about accuracy handloading techniques because that's what many readers seem interested in, and the techniques described almost always result in smaller groups, but perhaps more importantly, more consistent groups. We really don't need 1/2" groups (or even 1" groups) for a lot of shooting, but obviously quite a few handloaders like to dink with their rifles to obtain better accuracy, even those who mostly shoot big game at relatively modest ranges. Have noted before that this is probably due to rifle hunting seasons being open only part of the year, while handloading season is year-round.

That said, I do prefer 1/2" accuracy (usually for 5-shot groups, not 3-shot) for a lot of my varmint shooting.

Azar,
I start with brass with 2 thousand or less runout. I punch out the primer and remeasure. Then I size without the expander ball and remeasure. At this point I measure neck wall thickness as well. I then reinstall the expander ball but do not resize it and remeasure. I am still at 2-3 thousand. I then clean the primer pocket, trim and deburr. When I measure my loaded round is when I get 6-9 thousand of bullet runout. Its kinda frustrating.

Where is that measured? On the neck?

What is your tolerance for neck wall thickness?

I haven’t cleaned a primer pocket in 50 yrs.

I use Lee Collet neck sizer, don’t worry so much about neck thickness in hunting rounds. I do check neck wall thickness in some LR guns, like my 6.5-284, not so much the others. I check for runout, correct with a TruAngle tool and shoot half MOA groups with select loads. All my using rifles have premium barrels which doesn’t hurt.

I’m too lazy to do all that. I’m looking for max performance, min effort.

Works for me.

DF

John, naturally I have another question for you. Wouldn't inside neck reaming and then neck sizing with a type s die take care of any neck wall thickness problems? Thanks in advance.