Santa got me a Sinclair concentricity gauge, I love my wife. During use I found out that about half of my reloads are more than .004, but the other half was less than .002. I have read Rick Jamisons article in Shooting Times on how to set up seating dies, what the die instructions didnt say(rcbs standard dies). So I think my dies are set up ok, but Iam wondering if there is something else that is affecting the bad rounds, more than .004, and then come back and measure .001??? How good are the Hornady New Dimension seating dies? do they work as good as Reddings competition seating die? I know there is a big price difference. Going to a gun show in Boise this weekend and thinking about looking for some better seating dies....

What exactly did you measure? On the bullet, case neck, etc? Could be the bullet is not straight b/c the case is not straight. How does sized brass compare to fired? What about brass sized with no decapping pin? Are your cases neck turned?

Yep, have the same tool. Lots of questions and good reloading.

cheers

Havent been on this site for a while, so Iam a little rusty on the info.....I used the gauge on sized and fired brass and they looked really good at less than .0015. I was also measuring on the bullet. I dont remember the instructions mention anything about where on the bullet. So I have been using it just behind the ogive. And I havent made it to the neck turning game yet.

Take ten rounds measuring over .004 and keep them separate from ten rounds under .002 and go to the range and carefully shoot two ten shot groups alternating over .004 and under .002 but such that all ten shots over .004 are separate from the ten under .002.....and see what the difference is in the groups.

Any bets here?????

Yes, I have already seperated my good/bad rounds in 30-06. .308, and .300Win. Now its just getting time for the range. Hopefully Monday. I totally expect the good rounds to shoot better. I even check a round from Federal Gold Medal .308 Match and it was supprisingly over .006!

Well it sounds like you might want to give another seater a try. If you want a real kick, try an inline seater like the wilson.

Once I had a crooked decapping stem in one of my 223 dies. Concentricity varied from 0.005" to 0.001". As Vapodog suggested, I segregated and shot them, fully expecting the offending rounds to group worse than the straightest ones. Well, lets just say I need more data for a conclusive result (I could not tell any difference in my factory chamber).

Well thanks for the info. Hopefully I can find a Hornady New Dimension seating die for a good price at the gun show this weekend. Yes a new seating die might be in order. I really would like to get away with the Hornady, as the Redding is pretty pricey, worth it I bet, just out of my price range for now.

One more thought-- Give RCBS a call and see what they say. They are pretty good with customer service, might have some helpful suggestions.

You can buy all new dies, tweak the ones you have for lower runout, or best tweak your dies and then straighten your bullets with a Bersin tool............DJ

I haven't had any concentricity problems at all since I started using the Lee collet neck dies for sizing and the Redding competition seaters (or Forster Ultra benchrest seater) for bullet seating. Since I started using this combo, I've never had a round measure over .004", never (measuring on the seated bullet just behind the ogive with the Sinclair tool). The majority measure between .001 and .002" and in a batch of 20 reloads I'll usually have 4 or 5 that for all practical purposes don't move the dial at all.

If if becomes necessary to set the shoulder back a little and size the body of the case then I use a Redding body die for that. Otherwise I just neck size only using the Lee collet die.

Another quick point. I firmly believe the Forster Co-Ax press is a contributing factor also to the level of concentricity I'm getting in my reloads. I really like this press.

I feel your pain, having recently purchased a concentricity gauge and learning of the "deficiencies" in my loads. Your post leads to a couple of thoughts:

First, are measuring runout after sizing but before seating? The single biggest cause of out-of-round ammo in my (limited) experience is the expander ball pulling the neck off center. I've given up trying to find a "sweet spot" and put rubber o-rings under the stem of all my sizing dies. This allows the stem to free float and self-center- it's cheap and it works. Even better, get a Lee collet die, which gives virtually no runout and works the brass a lot less.

As far as seating dies, I've tinkered with a couple of Hornady New Dimension seaters and I'm not impressed. The concept seems to follow the Forster design of a sliding inline seater, but unlike the Forster there's no support for the case. I've only used a Forster competition seaters a few times, but they're great. I've never used the Redding competition seater, so I can't comment. My favorite are Wilson "hand" dies for seating.

My current obsession with loading concentric ammo has led me toward using a 3-die setup: a body die to bump the shoulder, a Lee Collet and one of the inline seaters. FYI, you don't have to buy a special body die- just pull the expander stem on your FL resizer and have the neck reamed out a touch so it doesn't touch the neck.

Now a disclaimer: as I said above, I am absolutely obsessed with concentricty right now... but I'm still not convinced that it has any dramatic influence on accuracy. But that's the beautiful thing about obsessions....

Oh, your making a mistake. I went down this road and came up very empty handed. But tad smarter. First off what you are seeing is about right. Second, don't just go off and buy a redding 60 dollar comp seating. Third, if you want to see where this is coming from, start cheap and get a sinclair neck thickness guage.

This was the source of all my bullet/neck runout issues. Cheap remington brass. What I did was start neck turning. Yes it corrected the bullet runout alot. But after you work the crap out of necks of new brass, you make it more out of round than it started, and have to fireform to get it right. This is contengent on your chamber being perfect. reason I neck turned, is remington is the only game in town for RUM brass.

Here is what I suggest. First start out with good brass. Lapura, Norma are a good place to start. Buy the neck guage. And see which pieces of brass have neck thickness varying more than .002". Second, deburr the inside of necks before seating. Third, neck runout alot of the time is from FL sizing or poor lube in the neck while sizing. What I do is deprime in one step and then raise my expander ball to the top of the die. This way, it expands as soon as coming out of the die and the brass is supported.

Other options. Sort loaded rounds and note whats what. I sort mine by less than .002", .002" to .004", and >.004" bullet runout. With guns with a bit of freebore, bullet runout does make a difference. With guns like my 308win, not really.

Bigcountry

I'am just getting into reloading again after 25 years of not reloading. My friend has a great set up that I will be able to use, basically anything you need and then some.

He uses your method of sorting brass, neck turning, etc. and is really into getting everything centered even in his gun.

I will be loading 300 win mag with norma brass and was wondering with the short neck will I have more issues, because of that.

I was hoping to be able to just neck size, but from what I have read, that can cause centering problems as well. Any thoughts?

I FL size the brass first and tighten the die when the case is all the way in (this squares the die body). Then,..I use the K&M expander iron which opens up the neck just enough to have to lube it to get it on the turning shaft, then turn the necks. Hold the turning body loosely so it can wobble, which allows the necks to be turned more uniformly (when they are that tight on the mandral, it is hard to mess it up anyway) and then your thickness will be within .0005" and can be gotten even closer on a second turning after fire forming.

My RUM brass is all within .0005" and the worst cases are at .002" bullet runout,...more than adeqaute for match shooting.

I have loaded for the 300win mag, and havn't had too many issues. No more than my 300RUM. One thing that helps me alot after sorting by neck thickness variation and then sorting more buy neck runout, is to rotate my brass while seating. I have the redding comp seaters. They do help, but not anything I can't do with a regular RCBS seater. The critical thing is one to chamfer the mouth real good, and rotating 1/4 turn while seating. In other words I put the bullet in the mouth. I raise it up until it touches the seating (really hasn't gone in much), and I rotate my brass, I push it up again a tad harder, and pull out and rotate again. I do this about 4 times until the bullet is 40% in the case. I then finish it off by seating all the way.

It sounds like a alot. But if your quick with press handle and both hands, its not that bad. And the pay off is worth it.

I let the weight of the handle start the boattail and sqaure it up,..then spin the case, and seat 1/2 way,..then spin it again and finish the seating. It DOES make a difference.

I too got a gauge.I have driven myself nuts w/it.But a man can't have too many toys.
I tried the 1/2 turn seating that JustC mentioned and it really brought it down.
Thanks,JustC.

I was wondering if I was nuts turning the case three times in the neck sizer to get it right, but I guess not. I've found my RCBS neck sizer would leave about .005 runout with one pass, and about .002 with three passes. Sure, I'm probably work hardening the neck, but I doubt that has as much effect on accuracy as a non-concentric bullet.

I'm in the process of turning my .224dia insert down to fit the 204 Ruger's diameter so I can turn the necks. This should indeed help with runout.

Thanks for making me feel normal.

Jim

Thanks for the info... That idea about rotating the round a few times in the seating die sounds like it works......now I just need to get my gauge back from my friend(i let him try it), so I can try this method....

Whiplash, don't test your loads at 100yds. Test at 300 or longer. The longer the range the more evident the effects of concentricity become. Concentrucity matters a lot way out there but you also need a rifle capable of a very high degree of accuracy. That Bersin device another poster mentioned is also very useful. With it and your Sinclair tool you can effectively reduce runout to near zero. You might also consider having custom dies made from cases fired in your rifle. Try rotating the case 180 in the shellholder after resizeing then run the case in again. Another trick is to loosen the decapping pin or screw it in against an rubber O ring to allow some flex and self alignment as you resize. Try this stuff and then measure with your Sinclair tool. Sometimes it helps and sometimes not.

I have an RCBS Case Master, and drove myself crazy with concentricity for a month or so. I used hard rubber washers from faucet repair kits to free-float the sizer balls, turned the cartridge 2 or 3 times during bullet seating, turned case necks.
I found consistent case neck thickness usually produces the best concentricity.
I've also seperated cartridges into groups of "best" and "worst", and found often times my "best" groups were attained with the "worst" concentricity.
Go figure...
Regards, George

Do you have to pull hard to remove your case from the sizing die? Most concentricity problems are associated with the sizing die not the seater. I cured this problem by switching to the Redding Bushing NS die, and their Competition seater. With some calibers I just have the sizer, and it really knocks the out of roundness down a good bit. The Wilson NS bushing knock out die works well also. I agree with turning the case in the seater half way around while seating. That'll bring it down some, but I thing the Redding and Wilson mentioned are your best bet. Best wishes.

Cal - Montreal

I have some questions to ask about concentricity. If you have a custom sizing die made to size .0015 at the base and at the large part of the neck. then a bushing installed for neck sizing (of the correct size). this should size your brass true (maybe .001 runout). then if we had a Redding Competition seater with the floating bushing made to a size to fit the sized case and the correct neck size for the brass we are using, this would keep everything straight. It looks like it should work. anyone have any comments on this.
Thanks