I was tinkering around with my RCBS Casemaster gauge this afternoon. I was checking the runout of some sized Sellier & Bellot 6.5 x 55 brass cases after they had come out of the Lee full length sizing die.

I noted totally unacceptable runout on most of the case necks, blamed primarily on the brass necks since my Winchester cases didn't exhibit near as much runout as the S&B's did.

I have already tuned this sizing die to center the expander (as mentioned by Don Krakenberger here, and confirmed on the RCBS gauge), so I initially thought that the runout problem couldn't be solved without turning the necks on the S&B cases.

However, on a whim I tried the following:

I rolled the case on the runout gauge (RCBS Casemaster, as mentioned) until the "high" side of the brass neck was indexed on top.

I then picked the case up from the gauge with my index finger and thumb, allowing my index finger to mark the high side of the case.

I then put the case back into the shell holder, making note of the position of the "high side," and ran the case back into the sizer just enough to allow the expander to pass into the neck, and then I pulled the case back out.

I remeasured the runout, and noted that it had not improved.

I again rolled the case in the Casemaster gauge until I could mark the high side again, and as before I put the case back into the shell holder, this time with a 90 degree advance of the last position. I ran the case in and out, and runout had been cut by about half.

The runout was now about .004", still too much. (This would translate into .007" or so on the bullet ogive).

So I indexed the case in the die once again, this time taking it a bit farther around, perhaps 120 degrees or so. This time, the case came out with .001" of runout.

But would it work for the other cases?

Strangely enough, it did. I found that by indexing the cases to the same point in the sizing die (with the "high" side of the neck runout pointing that same direction each time) every case was taken from an average of .005" to .0015" or so. Some of those 20 cases had .008" to .010" of neck runout before indexing and resizing. Even these came down to .002" or less...

I share this experience in hopes that some of you might try this same technique for reducing case neck runout. The case neck is the primary cause of high runout in the finished cartridge--as mentioned before, a little runout in the case neck will compound after the bullet is seated.

The sizing die that I was using was a Lee RGB (read 10 bucks a set) die. I was pretty amazed to get the runout numbers I did with what many consider substandard brass, using low dollar dies.

I haven't given much thought as to why this worked, but I'm open to interpretations.

Anyway, if you get bored and have access to a runout gauge, please give this a try and share your results...

Dan Newberry
green 788

Dan, that is great news for you. I will have to try your suggestion.

Thanks Dan. I'll have to try that. - Dan

Dan, you answered a question that I have been wondering for some time know if brass has run out can it be fixed I guess so you did. You also gave me a good idea on a post I have running as which to buy next your results here make me beleave case gage next cronagraph later.

As I understand this you only ran the case back into the expanding button and did not neck it down again.

The only thing that I can think of is that the lubricant or surface of the button is not uniform and this causes more drag on one side than the other. If this is the case it cannot be a consistant or uniform cure.

How does the neck wall thickeness vary? What are you using for lubricant? How much? Where?

Try a Lee Collet die. Mine has all but eliminated case run out for me!

Great!
Another reason to spend hours in the reloading room giving myself a migraine.

Seriously, I have a batch of Winchester brass that is way out, over .006" even after FL sizing in my Type S sizer. I am printing out Green 788's post and will try his method after the football game is over(I have my priorities!)

Thanks for the tip

ZM

[ 01-12-2003, 06:48: Message edited by: Zeke ]

I tried pushing them all the way into the die the second time, and that gave equally good results. I just figured that if it would work well without working the case body a second time, all the better.

I just used a lube pad and RCBS case lube. I didn't use any lube inside the neck--only brush clean.

Anyway, it will be interesting to see if others can duplicate these results--or if I can duplicate them again!

I'm going to see how well things go with the Winchester cases tomorrow, and I might get the chance to post back...

Dan

Hmmmm, seems to me that if you resized with the high spot oriented one way and got no improvement, then you resized again with the high spot rotated and got considerable improvement, then wouldn't you have to conclude that the die is not perfectly concentric? I assume that what is happening is that you found the "sweet spot" by matching the high spot on the brass with the high spot on the die, such that the die presses against the flaw in the brass and bends it closer to perfect alignment. That's my best guess.

If what I've surmised is true, I think you could test the theory by first finding some brass with low runout on the neck. Full length size it in that die and you should come up with higher runout if the die is indeed imperfect. And with Lee dies costing so little, I'd chuck that one and try another. Lee dies are all I use for sizing, but I've had a few over the years that just didn't suit me for some reason, so I just replaced them with another Lee.

One of the bigger problems in causing runout is a ram that is not concentric with the die boss threads. Tolerances for presses are plus or minus .005" by ALL manufacturers. It is only by luck that the ram, boss and die threads are concentric and perfectly aligned. I went through several presses trying to eliminate this problem. The best I could do with any press was .002" offset on a Lyman Orange Crusher. The make of the press doesn't matter. It's the luck of the draw because of manufacturing tolerances. Before I went to the Forster Coax to help eliminate this problem I tried to determine in which direction is the offset. You can do that in several ways, all by indexing the components and checking with a dial indicator.

The first and easiest is to run a die into the boss without tightening it. Then, run the ram with appropriate shellholder up to the die. In most cases you will see the die move in one direction, which is opposite of the offset in the ram to the die boss threads. You can verify the exact direction with a dial indicator. This is the reason die adjustments are recommended with the shellholder forcefully in contact with the die before cinching it down. That squares the die to the centerline of the die, boss and ram and aligns everything. Once having done that you can check in the same manner for offset by rotating the shellholder after indexing it, along with all the other components.

By marking the shellholder and the head of a case head, and sizing it after proper die adjustment, you can determine in which direction the case is offset, then compensate properly for it. With the marked case checked in your concentricity gauge you can easily determine the direction of the offset, what introduces it, and correct it. I found that rotating 120� and running the case into die 3 times, most introduced offset can be eliminated. Sometimes 2 time rotating 180� is adequate. In each case where an expander is involved, you only move the brass past the exander one time.

This is a pretty common occurrence in sizing brass. Most reloaders don't check and truly don't know how concentric their cases are. It's certainly a proper step for extreme accuracy.

I Just got a RCBS casemaster gage & thought I'd give some of your ideas a try. I have had very little luck so far so I did some testing on my own & found that the neck runout matched the neck thickness difference which makes sence I think if my neck thinkness was off .004 the neck runout was about the same. Well i don't have a neck turner to give my theary a try can anyone tell me if they have ever found this or am I barking up the wrong tree? I Guess I will need more tools hope the wife understands.

green 788,

Funny coincidence, I just got a Case Master myself and did some similar testing. However, I think I came to some different conclusions.

First I checked sized-neck runout on some unfired R-P .30-06 cases, resized in Lee dies on a Lee press. They had about .004" runout -- probably not enough to matter but if I can make it better, what the heck.

So I checked some new, unprimed brass from the same lot and found it had essentially no measurable runout. Hmmm. I brushed the necks and lubed the cases and full-length sized them in the same dies (though my Lee press has now been replaced by a Redding Big Boss.) Instant .004" runout.

For grins I got out the set of Lyman dies left behind by the friend I'm renting the house from. Found some more new, zero-runout cases and full-length sized them. This time they still had no runout. Guess whose dies I'm using from now on?

On to a possibly more challenging issue, the .375 H&H. When I got my Redding dies, I noticed the expander/decapper is wildly off-center. So I called Redding and the tech there told me that their tests showed it would have no effect on accuracy, just turn it close enough to center that it will go through the flashhole.

Needless to say, I was skeptical, but had tried it anyway, again with new, unprimed Rem. cases, and became convinced since the rifle (Interarms Whitworth Express with a 2.5x Leupold compact) shoots MOA with virtually every load I've tried. So I was interested to check the runout here.

Unprimed cases had about zero runout. Ran them through the die -- still no runout. I grabbed a few rounds I have loaded with 235-gr. Speer SPs for my next range session -- 4 of 6 tested zero runout, the other 2 were at .004 or less.

You may have read John Barsness's article on the same subject -- available online at http://www.24hourcampfire.com/reloading_subpage.htm

Barsness says that with dies that pull the neck crooked, he gets good results by sizing without the expander, then putting it back in and pushing the cases through just enough to get it in and out of the neck.

However, he also says he culls out brass with over .001" unevenness in neck thickness -- which may help but gets tedious. I neck sorted a bunch of once-fired Lake City .223 yesterday and got about a 20% rejection rate. Hopefully the .280 brass I've got coming tomorrow will do better. If not I can use the culls for plinking ammo, though I just threw the .223 stuff away.

John

Get over any ideas that new brass is concentric - it never is. Fireforming is the best method to solve this problem. The best way to gage if it is your press causing the problem - check runout across many caliber/die combinations. If it is the press, then you will see runout in all your die sets.

More often than not, it is the expander ball pulling the neck off center. Redding solved this problem with a carbide floating expander. You can accomplish the same thing by loosening the lock nut on the de-priming/expander rod. You should remove the de-primer pin first so that you do not bend it. Allow the rod to float in the die as you run the case in. Then measure runout.

Another trick is to use an O-ring between the press and the die. This allows the die to move with the brass rather than pushing the neck off center. Runout can be madding to solve at times, however, changing to quality dies is the quickest way to ultimately cure the problem.

Another runout culprit most folks overlook can be found in the shell holder. Everything can be in perfect alignment, but if the shell holder base or shoulder is off, it will distort the brass. If you think it is the shell holder, simply index and mark your case on the high side, then rotate the shell holder to see if the runout changes orientation.

Remember, each time you ram a case into the die you are work-hardening the brass.

green: for a better reload I clean and champer the inside of the necks befor resizing, neck or fl. This improves case run out and consistent neck tension. I also rotate my cases when Iseat the bullets and most of the time the run out is hardly noticeable.
Dave

I find the primary cause of neck or bullet runout is uneven neck wall thickness. All of the other causes are secondary and don't matter as much.

I asked a long range target shooter what his case prep system was and he said first he turns all necks, trims to length, preps the primer pocket, FL sizes the case and then separates them into 1.0 gr lots by weight. This guy and his boss are really professional long range shooters and sell gear at matches, make actions and rifles for the purpose.

It's the neck wall thickness. Garbage in, garbage out.

I agree that neck thickness is of extreme importance. I checked the Sellier & Bellot brass and found the necks to be pretty good, most varied less than .001", so I was pleased with that.

My press makes very straight .270, 30-06, and .243 ammo, so I guess the problem is with the Lee die/shell holder alignment. I use the same shell holder for the other cartridges mentioned above, so the shell holder should be fine...

I did try the same technique I mentioned above with some 6.5 x 55 Winchester cases, and they too came down by 75% or better in runout.

At this point I think that the cases have rim thickness variations that cause the shell holder on the downstroke to pull harder on one side of the casing than the other. By indexing the "high" spot so that it is in the shell holder opening (and not bearing against anything) it seems that the cases can be pulled out of the sizing die straight, or at least straighter.

The Winchester cases had runout after sizing, but not as much as the S&B. The Winchesters were improved in the same manner, however. I suppose if the rim thickness is the problem, the Winchester cases have the same problem, just not as pronounced.

It was suggested on another board where I mentioned this issue that the bolt face in my rifle may not be square, and therefore causing the case head to be out of square with the case body. This seemed plausible, so I measured some fired cases from the rifle and they were square to the nearest .0003" or so, which is less than the error of my caliper, I would say. These cases were fired in an unissued Swedish Mauser, a rifle noted for its exacting tolerances, so I'm not inclined to think the rifle is doing anything to the cases. (They measure no runout at all before sizing).

I will try this on other calibers (chamberings) and see how it goes. Admittedly, I've only done this with the Lee 6.5 x 55 dies at this time...

Thanks for all the well thought out replies. You all have helped me think about some aspects of the whole issue I had not yet considered.

Dan

I had the same problem with my Lee FL dies and I called Lee Precision and discussed it with a technician. He told me it is usually caused by case neck thickness variations between manufacturers of brass. Thicker case necks cause the case neck to distort more upon ramming it into the die and also drag more on the expander button/rod when removed - thus causing runnout. A smaller expander could improve things.

Make sure your press ram is square at the top. I have a Lyman C-press that is out of square and that causes problems. Also, make sure your shell holder fits the extractor cut on the brass properly so that the cartridge base rests flat and square against the top of the shell holder.
Finally, try loosening your shell holder slightly to allow it to "wiggle". This could help compensate for variations.

I tried something very similar to what you are doing and got nothing but frustrated. I could not find a pattern for "what" was causing the runout. I indexed the cases prior to sizing and found no pattern. I indexed the stem and tried it at different locations. I indexed the die body and tried it at diferent locations. I indexed the shell holder ..... Nothing showed a consistant pattern.

At this time, I was loading for two different 222's. For one, I used neck turned brass, for the other, I used the same brand and lot of brass without the neck's turned. The unturned necks showed little variance in thickness (I don't remember right now the exact amount). The fired cases showed no runout from either rifle. However, when resized on the same die (neck sized), the neck turned brass came out with .001 or less runout and the unturned brass came out with up to .006 runout.

I finally gave up and turned the necks on all the brass and they ended up minimum runout. At the same time, I was working with 243 brass that was driving me crazy with runout. I turned the necks on this brass and it helped runout substantially.

I'm not sure what the answer is, but I don't bother messing around anymore. If the brass is giving me a lot of runout, I just turn the necks (or throw out the brass!)
John

To all,

What tool are you using to measure neck wall thickness--especially when faced with doing it in quantity....

Thanks

Roger

I use the RCBS Casemaster gauge, but it's tricky to set up and use for this purpose.

I'm sure there are better tools for measuring case neck thickness...

Dan

I just checked some new WW .220 Swift necks that had been sized and chamfered with the Case Master. I got realistic numbers when I held the vertical cylinder down on the case neck. This variation was about .0005". I held the cylinder down firmly with my left hand and rotated it back and forth a tiny bit. I read the low number and then rotated the case and repeated this technique.Then I tried measuring the neck wall thickness with a caliper and found that any burr on the outside of the neck opening throws that system off. But then I chamfered the outside of the necks again and sanded them and then the measurement agreed with the Case Master. The variation as read with the caliper was about zero but it's hard to read numbers that small with a caliper.

It's easy to sit here at the keyboard and conclude that all necks need to be turned. Turning is really quite a hassle and there is a cost besides the time. The neck may not hold the bullet tight enough, case life can be less and in general it's not necessary for most hunting rifle applications.

But the varmint season is almost here and now the accuracy demands are greater.

By the way I just loaded these rounds up without turning the necks. The runout with bullets seated was .003". These are test loads for a rebarrel rifle thats due in a couple of weeks. I will do more work on the loads if it's necessary.

It's a hassle to turn necks anyway on cases that are not fired. I just have to make another arbor that way.

A ball micrometer for measuring neck thickness is available from Sinclair. They have a couple.

Savage 99. I'm not saying all necks have to be turned. I shoot a lot of cartridges that have never seen a neck turner. I was just referencing a couple of cases I ran into. I believe ultimately, it comes down to the brass or the die. Furthermore, I don't think there is "one" explanation for all our problems!
John

I have been trying to get sub moa accuracy for some years, and only got it the last three trips to the range.

I changed so many things three trips ago, I don't know what made how much improvement.

But at that time I also got a Sinclair concentricity gage and I DO KNOW some of what causes some of my concentricity problems: the expander ball. Now I don't even use it. I half size the necks with the FL die with no stem in it.

I thought I had read it all or figured it all out, but Bob338's post surprised me.