measuring bullet runout

[atimmons]

I am new to measuring bullet and case runout.
Where does one measure the bullet runout and case runout?
What tolerances do you use for Benchrest, highpower?
I have the Sinclair tool to measure but only have an indicator that will go to .001.
Primarily measuring 6 Dasher, 223, and 308.
Thanks

 

[alf]

I usually measure the loaded bullet for runout at the ogive.

1000/600 BR match ammo, I shoot for .001 or under.

I spot check fired and/or sized cases for runout, but rely on the ogive measurement most.

 

[fdshuster]

atimmons: I also use and prefer the Sinclair tool, also have the RCBS Casemaster. For checking case necks, on an empty piece of brass I set the dial indicator mid-way down the case neck. For the loaded round I like it as close as possible to the ogive point-of-land-contact with the leade. Have never been able to tell any difference in group sizes with loaded round runouts of .002", so that's my "standard" for ammo used in a match. Practice, scope adjustment, first round fouler's, etc. are acceptable up to around .004". More than that and the bullet nose is marked with a black magic marker, and if it still shows excess runout with the next 1 or 2 loadings, it will be permanetly marked and used for "general purpose" only. As the distance increases (beyond 2 & 300 yds.) I try to use the "perfect" rounds only. If you want to get a surprise (?) check out some factory ammo sometime: I've found runouts of as much as .015" by some of the "big names". So much for the quality of some factory ammo.

 

[atimmons]

Thank you alf and fdshuster
That is about what I was anticipating on tolerance, just was unsure of where to measure.

 

[Mikem]

I made my runout tester some years ago, even before they were selling many. I had a Sterrett dial indicator and magnetic mount, so I mounted a steel plate on a hard wood base, and mounted V blocks on it.
I take my reading of the case neck in the middle of the neck, and the bullets runout just below the meplet on the bullets tip, this gives you the highest reading, but is the most accurate location to test. A .002" reading in the middle of the bullet, will be around .006" out close to the bullets tip.
M.

 

[nfhjr62]

Have a Hornady on order

 

[tenring]

I do not like to measure loaded round run out on the ogive. For consistency, you need to measure this below the ogive on the bullet diameter. Otherwise, your seated round must be spot on, and that is a tough accomplishment.

 

[Bob3700]

For what it is worth.

If you purchase good brass (Lapua) and have a quality set of BR dies, low bullet runout is something that should be a given.

I don't check it anymore and my targets show excellent scores.

Bob

 

[fdshuster]

Bob3700: I use nothing but Lapua for my 222 Rem., 223 Rem., 6ppc (220 Russian), 22 and 6BR's. and 308, Redding type S FL neck bushing dies with Forster Micrometer Ultra benchrest seaters, and a Sinclair Arbor press with Wilson chamber seating dies, using extreme care, and following all principals of accuracy loading, and can still get loaded round runouts of .003" to .004" with at least a few. For some reason, the 222 Rem. seems to be the worst, 6BR's the best, and the rest somewhere in-between. I believe it's main cause is a defect ( not all cases, of any brand are perfect) in some individual cases. How else to explain: out of 20 or 40 cases out of the same box, 3 or 4 may have up to .004" of runout, and all the others can be perfect? If it were a problem with the dies, or loading technique, they would all have similar amounts of runout. I also find it's usually the same cases, over and over again that have the same amount of runout, after 10, 20 or ? loadings, while the "perfect" ones remain perfect throughout their 30 or so reloadings.

 

[Mikem]

FDShuster, I agree with your statement, and I use almost the same tools you do, except I use a Co-Ax press.
In checking bullet runout over the years, and using only Lapua brass in 6BR, 22BR, and others that if you have a case that normally or always has notable run out, try marking the high side of the neck with a fine permanent marker. Then the next time you reload that case, check it again for runout and see if the new high side of the neck is not in the same place as the first mark.
I have found this to happen over 95% of the time.
I'm not inserting the cases in any orientation in the dies, so the cause has to be in the case. Either in the thickness of the case neck,(unturned necks) or the factories annealing process.
Try this and see if it doesn't happen to yours.
If you turn your necks, it will be interesting to see how they turn out.
M.

 

[fdshuster]

mike: yes, I agree with you also, and the Lapua cases that have the most varience in neck wall thickness, as measured with my tubing micrometer, ( as much as .0015"/ .013" to .0145" for example) will be the most likely to have the greatest loaded round neck runout. Outside neck turning for my tight-fitted necks ( 22BR, 6ppc, and 2 of my 4 6BR chamberings) will uniform the necks, but I believe the thickness varience extends into the case all the way to the head, from when it was formed/drawn: a defect "built-in" at that time, and when extreme, the typical "banana case". Surprisingly I've bought bulk 50 and 100 bags of Winchester and even Remington for my varmint (not benchrest) cartridges, and had some unexpected high quality, but then the next bag could be "not-so-good". Again, defective at the time of manufacture, for whatever reason. I've finally settled on segregating them with the Sinclair indicator, and using them according to their amount of runout. I'll try marking the "thick side" as you suggest/ have never done that. An older RCBS Rockchucker (not made in China) is used with the screw-in dies.

 

[Mikem]

Frank, I haven't tried marking the thick side, I marked the high side of the neck runout, but I think it would be the same, and you may have just confirmed all of my suspicions.
I have mentioned this before on this forum, and others, but think my post missed the mark, and went over some heads, but it sounds like you are aware of the same phenomenon. What you said about the thick wall continuing on down the inside of the case certainly is possible, they do weigh different, and often have more variation than just the neck could account for. But that's something that would be hard to measure.
Mike.

 

[aJR]

Hi all , started in 1997 making my own gauge to check runout , i used it to straighten all loaded rounds ..pic 1.. Then made a case gauge and progressed to a unit that would check Loaded round run out / case runout and case head squareness .pic 2.. I think it's worth the effort as you can see proof on the target at a 1000yds..JR..Jeff Rogers

 

[JRinCo]

Straighter is better!
The next time that you are shooting long range, pick out a round that has over .002 run-out and watch where it goes.

Over the weekend, I was setting up to turn the necks on some 6br cases ( Lapua brass) for a Dasher project ( this is my first experience with 6br cases). Right away the first case has .001 neck thickness variance. So I decided to check the rest of them and found that maybe 30% had allot of variance, while others were excellent. I haven't yet segregated them, but I'm going to before I even turn them. I'll use the perfect ones for record, and if there aren't enough perfect ones left for sighters, I'll have to use the mediocre cases. The rest of them will have to go prairie doggin.

 

[fdshuster]

JRinCo: There you go, my sentiments exactly. And that's with Lapua that has a known, generally agreed upon reputation of high quality. Imagine ( or measure neck wall thickness variation) of some of the big name "bulk" producers. I found one to have as much as .004": you could actually see the thick & thin by looking at the case mouth with the naked eye. I've not been able to see any difference at close ranges, and in some instances have gotten tighter groups with .003" when shot side-by-side with .001", but move out to 300 to 500 yd (my maximum available distance), and it is a factor.

 

[Mikem]

Its so refreshing to talk with others that think as I do about round concentricity (runout to me), so many blame it on dies, presses, or there reloading technique, when so much of the problem arrived in a box by UPS. Most here are talking about Lapua brass, but the problems would be much worse if it were brass of a lesser quality.
I shoot both 6BR and 22BR, among others, but chose to not go with turned necks (I don't shoot in competition) just for my own enjoyment.
I first started reloading in 1965, and back then we had concerns for runout, but just rolled the loaded case on a table and observed the bullet tip, and if we couldn't see any wobble, we shot it. But things have changed dramatically, as in the above pictures of the fine home made runout testing equipment made by Jeff. I also built mine back in 2000.
If your turning the necks, but first running the case through a die with a ball type expander, your moving all neck thickness aberrations to the necks outside surface, then turning it off. And I don't think it gets any better than that.
I have straitened bullet runout by placing an empty case over the bullet and pushing slightly, then retesting, but have not conducted any tests to see how much this helps at the paper end of things.
I'm just glad to see that others are taking an educated look at the problem, and sharing there experiences.
Mike.

 

[Bob3700]

Your observations on the run-out issues of long vs short cases is correct. With BR .PPC brass, you don't worry about it because the brass is good (Lapua) and it also is real short.

On longer cases 222 and 308, runout is an issue. What causes it? Could be the dies as all are not created equal. The real culprit is the brass itself.

Years ago Merril Martin (a PS writer and machinist) put a lot of effort into this very topic. Look up his articles on "Banana Cases". Basically what Merrill found was that the distribution of brass in the case is the issue. One side of the case is thick while the other is thin. Upon firing the brass bends like a banana, thin side stretches. Once the brass is fired (and bent) no die will straighten it out.

Some of you have already found this out. Place a mark on the thin or thick side and fire the case. Now check the neck run-out and see if the mark is at the same thin or thick side after firing. It will always come back. You cannot change the distribution of brass in the case.

Now the other technique that Merril tried is to index the loaded rounds in the chamber. That way, the bullet is presented to the throat the same each time. Flyers disappear this way. Down side is that you wear the throat in one spot if you don't rotate your indexing of loaded rounds in the chamber, firing 20 rds with a 12 o"clock index, the next 20 at 6 O"clock index etc.

The ultimate solution is to shoot short cases. If you have a long case, you need to be sorting your new brass by thickness just above the head of the case (second best is neck wall thickness variations). You are going to go thru a lot of Rem,Win,Fed brass to find brothers, but that will reduce/eliminate your loaded round run-outs.

Bob

 

[Laurie]

Bob, Frank, and Mike,

very interesting observations and experimental results - some new facts and ideas, as well as confirmation of some of the opinions and beliefs I've acquired over the years. Like you guys, I couldn't figure out why I'd get higher runout than I thought I should with a fair sized minority of rounds after I'd started using decent dies and other kit. Also like you, I've gradually come to think individual case internal concentricity plays a large, probably the single largest part in it.

I hadn't considered the long v short case matter before - I'd always just thought Lapua put more effort into making its 220 Russian, 6BR and more recently 6.5X47L brass, but I'm sure your views on short designs being intrinsically more likely to be drawn with consistent walls are valid.

Another thing I found last winter when I was preparing my .308 cases for the 2009 season was that running new but sized Lapua cases over a Sinclair concentricity gauge produced a handful - less than 1% - where the whole case seems to be out of true, but doesn't show any obvious serious defect as in large neck thickness variations. Whether fireforming these cases would solve the problem, I don't know and haven't tried.

Incidentally, when I first got my Sinclair gauge some years back, and my first precision ammunition measuring / preparation type tools, I soon decided that using it was a shortcut to the lunatic asylum given some of the results, and put it on one side barely using it for a year or two. A lot of this was down to 'horses for courses' as I was still handloading a lot of ammo for historic military arms, and a combination of poor quality brass and huge and probably none too concentric chambers saw some horrific runouts. I can still remember measuring 50 rounds of the last 0.303" ammo I ever handloaded that used Greek HXP arsenal brass and getting runouts that literally ran from one or two thou' to nearly 30 thou', most in double figures! I was in despair, and started to think about pulling the rounds, emergency purchase of new / better dies etc, then I thought "What the hell ...... ?" and went and used it, having one of my best ever results with my old Winchester P'14. The rifle of course just couldn't tell the difference between 'good' and 'bad' ammo, concentricity wise. What it did like and respond to was Sierra MatchKings instead of military type FMJs and given how slack the chamber was, it obviously didn't matter that they weren't seated too straight. The other factor that I realise now but didn't then was I used to invariably neck-size in those days believing that fireformed cases would produce more accurate ammo, but with the rifles involved, I'm now pretty sure I'd have got more concentric ammo by full-length sizing as long as the headspace was kept under control.

Today, with gunsmith chambered barrels, match quality brass and really good tools, it's a completely different ballgame!

Laurie,
York, England

 

[deadlyswift]

Great info guys! Although I couldn't have put this into words that all of you have. I had some what the same pic in my head.

Now tell me if this is a bad Idea, good Idea, or if my steps an process is wrong?

1. size brass (redding fl type s bushing die.)
2. uniform primer pockets. (sinclair's uniformer with power drill adapter)
3. Trim all cases to exact length. (Redding micro trimmer.)
4. Sort cases by wieght. (RCBS powder pro digtal scale)
5. Sort cases again by neck wall thickness. (Sinclair's Concentricity Gauge)


I am just learning about runout and the differance to how it affects groups at longranges. I do understand the concept of what runout is and how to check for it. I am about to start with 200 pe of .308 lapua brass and I don't want to take the wrong steps and mess up 200pe of expensive brass. My above steps is minus deburring the flashhole. Upon my first obbservation of the brass when I got it shows no burrs. I'm assuming this is lapua brass.I either read it or someone told me that lapua punches there flah holes where win. drills there flasholes leaving a burr on the inside of the flashole. I hope I'm not stealing the thread here. I just thought this would be a good place to ask my question since everyone is on the topic.
Thanks

 

[Laurie]

Deadlyswift,

that seems a reasonable programme for case preparation and selection. In fact, you probably don't need to uniform the primer pockets on Lapua brass for anything other than the very longest range F-Class or similar, but you're certainly not going to ruin any cases.

You do have one thing the wrong way around though - Lapua, Norma and RWS machine the primer pockets on their cases and drill the flash-holes, while Remchester etc swage / punch them. You sometimes get tiny burrs on the inside edge of the of Lapua flash-hole, but they are small. With the punched stuff, you can get really big spikes left around the inside hole surfaces. Also, Remchester, Hornady etc brass usually has a markedly concave floor to the primer pocket, and as soon as you use a Sinclair or whoever's uniforming cutter on them, you see how how much variation there is between cases. So, I regard primer pocket uniforming and flash-hole deburring as essential processes for the American made brass, unless it's only going to be used at short ranges.

I hope this helps.

Laurie