Runout Is Dead / Long Live Runout

[CarlGeorge]

Through misc runout threads I've seen in this forum over the years I've generally seen two things espoused:

• Measuring runout at each step of the prep/reloading process is a good reloading process diagnosis tool and will help one figure out which step(s) in their process are candidates for improvement.
• Runout in finished rounds, generally, doesn't impact performance on paper.

What I don't get is: If the second statement is true, why do ANYTHING related to the first statement? Why bother with even measuring it and trying to correct it? For example, maybe I find it's my sizing operation that is introducing runout in my reloading "system". If it doesn't impact results on paper, why do I need to know or care about resolving runout due to sizing? (Or....any of the other steps.)

 

[Jager]

Great question, Carl. For those who don't think runout matters, I think you've described the end game quite well.

For those of us who think the bullet's orientation to the bore does matter, well then there's more to talk about.

 

[Falfan2017]

Do you need less than .002” of runout to shoot well? No. However measuring runout can alert you to problems you may not be aware of. I had a bushing that wasn’t fitting the bushing sizer correctly. Was able to figure that out by measuring runout at each step to see where the problem was.

Same idea as measuring seating pressure. The pressure may not matter much but if you’re getting extremes in either direction it can alert you to other problems.

 

[jelenko]

I would add that it also depend on the accuracy level you need. What you need to pay attention to get .1 to .2 MOA is different from what you need to pay attention to for .5 to .75 MOA.

 

[Alex Wheeler]

You have to also look at the chamber. Lets assume a 6BRA.
A loaded round (properly sized) inside a chamber has about .0005" clearance at the base, .002 at the shoulder, and about .0007" around the bullet. So, once chambered I do not think a round could have much over .002" runout, the way we measure it. I have never been able to see the difference between .000 and .002" runout.

 

[CarlGeorge]

Thanks for the replies. They made me realize I didn't give much specifics or context for the question.

I have an F-Class rig I'm trying to dial in. (Kelbly Atlas, Brux 30" barrel, McMillan Kestros stock. At 100 yds with minimal wind....which I only mention because I'm trying to take out other factors such as my (low) ability to read and compensate for wind at longer distances.....I'm getting about 1/3 MOA or so. I'd like to tighten that up - which I presume isn't an unreasonable goal given the setup I have.) I don't ACTUALLY shoot F-Class now. I'm just pursuing everything as if I might. The project of getting this thing dialed in and gaining some proficiency on the 1,000 yd is interesting and satisfying enough for me for the time being.....even if I haven't yet entered a match.

My sizing operation is introducing case runout into the equation - generally about .002" but I've seen as much as .003". I've played with looseness of the bushing (I'm using a bushing FL die). It's a Redding die. I was wondering if a Wilson die would help. But then I started wondering if .002-.003" of additional runout after sizing was significant.....which caused me to remember folks here saying "One rarely sees runout as causation for group size."......which lead to the post.

 

[K22]

Does it matter? Maybe, probably - the more consistent the reload the better right? That's what the goal is right? Sure it is - that just makes sense. But wait, there's more.

Does it translate to performance? That is the question I ask when I consider expanding my dreaded reloading process. As "jelenko" stated, a lot may depend on the precision level you need for your game. If I'm in the 1/2 to 5/8" moa range for my varmint / predator rifles I'm happy since I'm only shooting at the most, out to distances of 275 to 300 yards; modest by today's standards but it's all I need for my game.

Years ago I experimented with measuring round run using plain old RCBS dies with and without O rings under the die or expander ball assembly and the effect of paper. Even though the measurements varied (can't remember the exact numbers) I found no noticeable affect on performance. Surprising, the O ring under the expander ball assembly, allowing it to float, gave me the best measurements but again - it didn't translate to improve precision.

Gross run out is something different. The old school occasional test of rolling a round on a level smooth surface and not seeing a visibly detectable wobble seems to work to detect gross misalignment.

The internet has created a lot of premises on shooting and reloading - some sound - some maybe not so sound. I always like to verify that a particular prescribed process translates to performance improvement on paper or improved reliability. I will shamefully admit that I uniform primer pockets but I can't say that rounds prepared as such shoot any better than one's I don't uniform. The only thing I can say about it is that it makes it a lot easier to clean the pockets.

I'm fairly leery of "absolutes". Just check out the internet YouTube video's on cleaning / reloading and you'll will see such a wide range of "expert" opinions that you'll need a double martini afterwards. I personally find it amusing.

 

[Jud96]

I don’t think it matters. If you have .005 of runout and you chamber the round in a throat that’s 0.0005-0.001 over bullet diameter then the bullet will align to the throat. The bullet will not remain crooked because the barrel will straighten it. That’s my theory at least.

 

[Acyr]

.002 runout is fine. If you want to shoot 1000 yard f class spend your time learning to read the wind and stop worrying about the small stuff.

 

[Uncle Ed]

"runout" a picture is worth a thousand words...............what would you do if someone told you to get bent?

 

[Intheshop]

Wringing out cast in varmint rigs,running around 3k fps;

There's a good 1/2 dz things that need to be well sorted before we get to runout. And like most things,it isn't always "just" one aspect.

Cast bullets are extremely vulnerable in the seating op. Can't fully explain the relationship in how the stem's internal shape,and finish effects runout. The grip between the bullet and the stem is higher than with JB's.... which will self align better. So the steps leading up to,and including seating have a direct effect. But any more than that? beats me. Have made a bunch of seaters,some work better than others,but that's not the point.

The point is the process leading up to getting good runout numbers.

Some of these ops have input on how well they're gonna shoot. So,to simply say..... "these rounds have less R.O. so they'll shoot better",isn't quite the whole story. How clean your process was plays a role,like the relationship of the seater to bullet.

The two things that noticeably,upped the game for me(jacketed velocity out of cast varmint rigs) were,annealing and deadnuts straight ammo. But it wasn't "just" the softer brass,straighter ammo. It's how these things helped,and were helped by,other aspects of the process. Very tough to put into writing.

Good luck with your project.

 

[KMart]

For me, ignorance is bliss. One less tool to buy but only because I am out of storage space. I have everything else.
Do the short range BR guys measure runout on every round they load before shooting the next relay? Never been to a BR match, so I don't know.
If I could just get the wind to blow at a constant speed from a consistent direction and find a target where the x ring doesn't jump all around, I would have this game figured out!

 

[Uncle Ed]

Below the Forster full length bench rest die with its high mounted floating expander. The case neck is held and centered in the neck of the die when the expander enters the case neck. Meaning the expander can not pull the case neck off center and induce neck runout.

Below I installed a modified Forster expander and spindle assembly on my Redding dies. This greatly reduced case neck runout when sizing. The modification was cutting the spindle to the proper length and adding a rubber o-ring under the expander lock ring.

Below from the Redding bushing die FAQ

Tech Line & Tips (FAQs)​

Concentricity Problems​

a.k.a Neck Runout With Bottleneck Cases

"We have conducted many tests over the years on the various factors contributing to concentricity problems with bottleneck cases. We have repeatedly found a definite correlation between the uniformity of the brass (or lack of it) and the resulting concentricity of the neck to the body of the case.

An interesting experiment also revealed that neck turning of brass that was intentionally sorted as non-uniform, showed little or no concentricity improvement when used in standard S.A.A.M.I. spec chambers. Conversely brass that was sorted and selected for uniformity remained uniform and concentric with or without a neck turning operation."

Below I use the Redding neck thickness gauge to sort my cases. With one twist of your wrist, you will know the quality and uniformity of each case.

What Redding is telling you is you can't make a silk purse from a sows ear. Meaning uniform quality brass has a great deal to do with case neck runout no matter how it is resized.

One of the biggest causes of neck runout is if the expander is locked down off center. And the Forster high mounted floating expander can not pull your necks off center.

 

[dstoenner]

I run every batch of ammo across my runout gauge. I shoot fclass so i sort out the 1’s and 2’s for record shots and sighters. I need 72 for a match and my batches are 90+ as a matched set. The remainder gets used for a velocity and zero check at 100 yards. Most of those are 3’s.

That said, i wondered about that back when i was shooting nra high power. Using LC cases you can get some bigger runout so i collected 10 that were around .007 to .010 in runout. I fired 1 group of 5 of my .002’s then a 5 shot group of the high runout. Did that twice. The groups of 2’s did about .450 average. The group of 7’s averaged around .750. So it does matter some but a group of .750 is still inside the x ring of a MR31.

For me i try to average 70% of a match prepared match set to be 1’s and 2’s. If i can run that it is good. And i have spent a lot of time diagnosing the steps to get me there.

HTH

David

 

[Uncle Ed]

Save $$ By Using Lake City 5.56x45mm Once-Fired GI Brass​

http://bulletin.accurateshooter.com/2019/10/save-by-using-lake-city-5-56x45mm-once-fired-gi-brass/

Accuracy Potential of Mil-Surp 5.56×45 Brass​

So, how accurate can previously-fired GI surplus brass be in a good National Match AR-15? Well, here’s a data point from many years ago that might be of interest. A High Power shooter who wrote for the late Precision Shooting magazine took a Bill Wylde-built AR match rifle to a registered Benchrest match. His first 5-round group ever fired in a BR match was officially measured at 0.231″ at 200 hundred yards. This was fired in front of witnesses, while using a moving target backer that confirmed all five rounds were fired.

He recounted that his ammo was loaded progressively with factory 52gr match bullets and a spherical powder using mixed years of LC brass with no special preparation whatsoever. Obviously, this was “exceptional”. However, he had no difficulty obtaining consistent 0.5-0.6 MOA accuracy at 200 yards using LC brass and a generic “practice” load that was not tuned to his rifle.

 

[Oleg S]

Thanks for the replies. They made me realize I didn't give much specifics or context for the question.

I have an F-Class rig I'm trying to dial in. (Kelbly Atlas, Brux 30" barrel, McMillan Kestros stock. At 100 yds with minimal wind....which I only mention because I'm trying to take out other factors such as my (low) ability to read and compensate for wind at longer distances.....I'm getting about 1/3 MOA or so. I'd like to tighten that up - which I presume isn't an unreasonable goal given the setup I have.) I don't ACTUALLY shoot F-Class now. I'm just pursuing everything as if I might. The project of getting this thing dialed in and gaining some proficiency on the 1,000 yd is interesting and satisfying enough for me for the time being.....even if I haven't yet entered a match.

My sizing operation is introducing case runout into the equation - generally about .002" but I've seen as much as .003". I've played with looseness of the bushing (I'm using a bushing FL die). It's a Redding die. I was wondering if a Wilson die would help. But then I started wondering if .002-.003" of additional runout after sizing was significant.....which caused me to remember folks here saying "One rarely sees runout as causation for group size."......which lead to the post.

Bushing generates runout. If you already settled on size for necks, I suggest ordering NON bushing die.
Forster or other people can make you FL sizing non-bushing die with inside neck diameter you like.

 

[dkhunt14]

"runout" a picture is worth a thousand words...............what would you do if someone told you to get bent?

Years ago my buddy didn't like neck turning. He used 300 Weatherby to make his 308 Baer cases. When using the 300 case, it was thinner and didn't need to be turned. Everybody else used 340 Weatherby cases and when necked down they got thicker. Now they needed turned. I made him up a set of turned brass from the 340. I loaded them for him and I don't know what happened, but I had one that was really crooked. Maybe even worse then the one you show above.

I shot these shells in the Banquet shoot with his gun. I picked out the crooked one and set it to the side. He was on the line with me and said why didn't you shoot that one? I said I didn't want to chance hurting your gun. He took that shell and put it in the tray, pushed the bolt forward and took his hand and beat the bolt shut. I fired it and it went right in the patch where the previous sighters went. This was at 1000 yards. It didn't seem to matter for that shell. Matt

 

[dkhunt14]

Thanks for the replies. They made me realize I didn't give much specifics or context for the question.

I have an F-Class rig I'm trying to dial in. (Kelbly Atlas, Brux 30" barrel, McMillan Kestros stock. At 100 yds with minimal wind....which I only mention because I'm trying to take out other factors such as my (low) ability to read and compensate for wind at longer distances.....I'm getting about 1/3 MOA or so. I'd like to tighten that up - which I presume isn't an unreasonable goal given the setup I have.) I don't ACTUALLY shoot F-Class now. I'm just pursuing everything as if I might. The project of getting this thing dialed in and gaining some proficiency on the 1,000 yd is interesting and satisfying enough for me for the time being.....even if I haven't yet entered a match.

My sizing operation is introducing case runout into the equation - generally about .002" but I've seen as much as .003". I've played with looseness of the bushing (I'm using a bushing FL die). It's a Redding die. I was wondering if a Wilson die would help. But then I started wondering if .002-.003" of additional runout after sizing was significant.....which caused me to remember folks here saying "One rarely sees runout as causation for group size."......which lead to the post.

The thing I learned about 1000 yard shooting is most times you can't rely on what a gun does at 100 yards to shoot at 1000 yards. A good example is I have had guns that would great ES and in the zeros and ones at 100 and the smallest they would shoot at 1000 was 13 inches and all vertical. That same gun with a different load would shoot bigger ES and 1/2 MOA and bigger at 100 yards and would shoot 3 and 4 inch nice round groups at 1000. I had way more then one gun do this and seen many more do the same.

Some of them were 80 pound heavy guns used in 1000 yard BR and that pretty much shows it was the load that did it. I think you need to worry more about some other things and test a little farther out. I like 400 yards minimum. I believe that you can watch conditions good enough and it will show you more what the load can do.
I also try to test early in the morning or late in the evening when the winds are really good. Matt

 

[PracticalTactical]

I know this is an old thread but I don't see anyone talking about why people have mixed opinions on runout.

The first point to consider is the length and diameter of the free bore of the rifle in question.

To this point, a rifle with short free bore dose not rely upon the free bore to create bullet alignment to the rifling. The counterpart to that is a long free bore... Keep in mind that free bore is not always the same diameter or length, so a guy with a long tight free bore has the advantage of ensuring the bullets is guided perfectly into the rifling, while a guy with an over size free bore cannot, regardless of free bore length.

With this in mind, results developed with one throat condition cannot be arbitrarily applied to all other rifles regardless of the throat dimensions.

The next thing to think about is neck damage caused at ejection.... If you have a controlled round feed action like a Mauser, the case is not ejected until well clear of contact with the action. As a result the necks are not damaged in the process.

A Rem 700 style action will physically deform the neck by smacking it into the side wall on the way out. So the D shaped mouth is ripe for runout challenges as it is offset before it enters the die. Target shooters will cut the ejector spring shorter to reduce or eliminate this problem.

The next thing to consider is neck clearance. With this in mind, and assuming your necks are not being damaged at ejection, the amount of neck resizing needs to be considered.

In other words, you cannot create 0.005" of runout if you are only sizing the neck 0.002". With this in mind, the tighter the neck clearances you have, the less you need to resize the necks and the less runout you will have.

If you are reducing the neck diameter by 0.014" then you can theoretically create up to 0.014" of runout.

Furthermore, if you are sizing your necks this much with a bushing die, you will create a taper to the neck. The mouth of the case will be smaller than half way down the neck.

To straighten out the neck, its good to size it one more time with the neck smaller bushing.

When it come to runout, the most perfect case you will have is one that was fired in your rifle. Anything you do to that case from there is creating variability.

 

[BoydAllen]

Below the Forster full length bench rest die with its high mounted floating expander. The case neck is held and centered in the neck of the die when the expander enters the case neck. Meaning the expander can not pull the case neck off center and induce neck runout.

Below I installed a modified Forster expander and spindle assembly on my Redding dies. This greatly reduced case neck runout when sizing. The modification was cutting the spindle to the proper length and adding a rubber o-ring under the expander lock ring.

Below from the Redding bushing die FAQ

Tech Line & Tips (FAQs)​

Concentricity Problems​

a.k.a Neck Runout With Bottleneck Cases

"We have conducted many tests over the years on the various factors contributing to concentricity problems with bottleneck cases. We have repeatedly found a definite correlation between the uniformity of the brass (or lack of it) and the resulting concentricity of the neck to the body of the case.

An interesting experiment also revealed that neck turning of brass that was intentionally sorted as non-uniform, showed little or no concentricity improvement when used in standard S.A.A.M.I. spec chambers. Conversely brass that was sorted and selected for uniformity remained uniform and concentric with or without a neck turning operation."

Below I use the Redding neck thickness gauge to sort my cases. With one twist of your wrist, you will know the quality and uniformity of each case.

What Redding is telling you is you can't make a silk purse from a sows ear. Meaning uniform quality brass has a great deal to do with case neck runout no matter how it is resized.

One of the biggest causes of neck runout is if the expander is locked down off center. And the Forster high mounted floating expander can not pull your necks off center.

On expander balls and crooked necks: If you investigate even a little bit, what you will normally see is necks at an angle to the centerline of the body of the case. This is generally caused when the die's neck ID is considerably undersized so that the expander has so much work to do that the axial pull on the case exceeds the yield strength of the brass at the shoulder. The case shoulder is pulled out of shape by the pull on the neck. Because of runout in case wall thickness the shoulder yields asymmetrically which results in a cocked case neck. Further evidence of this angularity will be see by measuring loaded round runout at various distances from the case mouth. Typically, the farther from the case you get, the higher the number. This is not to say that The position of the Forster expander in not advantageous, but rather to correct the part about necks being pulled off center. The other issue is how small a die maker chooses to make the ID of the neck portion of a particular die. If is dies neck IDs are less undersized that will help.