Accurate Reloading------Bullet Straightness/Runout

B

Bigdog2

New member
It’s really quite amazing all the “extra” techniques that are available to reloaders in search of obtaining the ultimate in accuracy. Of course “accuracy” itself means different things to different people. To the target shooter it might be a one-hole group, to a prairie dog shooter it might be red-mist at 300 yard, to Deer and Elk hunters it might be being able to hit a 6” or 8” pie-plate at 200 yards.

These extra techniques might include one or all of the following:
Brass from only one manufacturer, and
Only one lot or run of Brass from that manufacturer, and
Cases sorted by weight ranges, and
Only one brand of Primer, and
With Primer pockets of uniform dimensions, and
Deburred Primer holes, and
Full length sized cases, or
Only Neck Sized cases, with
Uniform Neck Thickness, Inside and/or Outside, and
Chamfered case mouths, and
Uniform Overall Case Length, and
Bullets seated only certain distances from the lands,
Bullets seated to specific Over All Length
Bullet Selection for specific uses with all
the variations that manufacturers can muster, such
as materials, points, shapes, weights, etc., and’
Bullet Runout or Bullet Straightness
There must be more, please let me know if you have a favorite not listed. And of course these are only what we can do to control the bullet/case/cartridge/primer& powder side of the equation.

My Question

The above list is the long way of getting around to asking if any of you have any experience in finding the amount of accuracy improvement that can be obtained by minimizing Bullet Runout or maximizing the Straightness of a loaded cartridge?

Are you using a Forster Case and Cartridge Inspector Gauge or an RCBS CaseMaster Gauging Tool to determine runout? Do you use a special Seating Die to help seat the bullet?

Or is this topic, like many of those listed above, only important to the Target Shooter or to someone that is trying to sell reloaders more stuff? (Sorry if that sounds a bit defensive)
 
I'll give a quick anecdote on runout. I got a new Savage 12 FVSS-S in 220 swift. New brass was neck sized only. It was fired with several powders and 58 gr Vmax and 55 gr Sierras. Accuract was pretty good with about half MOA or less. Full length resized cases and back to range with refined loads. Most groups were significantly larger. At the same time I went halves on a Sinclair concentricity gauge. Runout on new brass was almost zero. Full lenght sized was about .012-.020. Fire formed cases w/o FL resize back to .000 - .002. Collet sized fire formed cased and reloaded, runout less than .004 w/ most .001 - .002. Back to the range with same load data that gave bad groups and nearly all were less than .5".

The moral is a bad die introducing non-concentricity to the brass significantly affected the accuracy. When mentioning it to friends they all had similar horror stories from something gone awry in the loading process. I am a casual shooter, not a bench rest/palma type, but I like guns to perform
 
I have tested runout over the years and, within a reasonable runout, a couple thousandths, you will only be able to measure the difference with a very accurate rifle. You get up there in the .012-.020 range jagrdawger is talking about and you could probably measure the difference with even an average factory rifle. That much runout is pretty rare and indicates a serious problem somewhere.

Jack
 
Runout is one of the most overlooked and IMHO one of the most important factors in accuracy reloading. I use a NECO gauge and like it.

For normal hunting range "minute of coyote" accuracy, I think runout is still important, but just rolling your ammo on a mirror will probably be more than sufficient.
 
Imangine a line from the center of the primer through the tip of the bullet. The bullet should be able to spin on that line or axis with no wobble. Wobble means that the loaded round is not perfectly symetrical or concentric. When it is fired in a barrel it will not be exactly centered with the exact center axis of the bore. This will induce wobble and slight or maybe more inaccuracy since each round will wobble though the barrel differently. The wobble is seen in the mirror better because the error appears magnified since the relection wobbles also. Concentricity gauges use a micrometer to measure the concentricity to the nearest .0005-.001 depending on the make. Dies, neck thickness, malformed bullets can all add to concentricity problems.

In my case the FL sizer die was not cut right and was pulling the neck over to one side by .010-.020". More than about .004 is the number I have heard some of the Army morksmanship team talk about as an issue, although these guys sorted their ammo down to .001 for the match and .002-.004 was practice.
 
turning the high spots on the necks is usually good for taking out .001-.002" runout with no other modifications.

also, a seater die with a sliding sleeve that holds the case in concentricity with the seater plug also makes a difference.

I had the gunsmith take my redding competition 6.5x55 die sleeve and run the Improved reamer in it to make the internal dimension of the sleeve a perfect match to the fired 6.5x55AI case dimensions, and have runout of .001" max.

you can win a match with a few .001"s runout, but after that you better be happy with something other than first place. As distance increases, your runout will come back to bite you.

Bottom line, there are many many tricks to try with respect to your dies and your brass and your tools etc. This is the time consuming part of handloading that actually forces you to learn about every detail and every aspect of your equipment.
 
Changing the lock ring that use the lock screw against the threads to the older type that squeezes the lock-ring against the threads (Hornady Type) will also be one extra simple step to take.

Also, I will take 2 shell holders and place them onto the PRESS RAM so that I can get a completely flat surface to mate against the seating die to make sure that the die is inline with the shell holder (The single shell holder in the ram usually will not make contact with the bottom of the seating die, so it may not be inline). Then I will tighten the lock-ring down.

Just a couple of other things you may want to try that do not cost anything other than time.

As far as the question of which concentricity gauge I use? I use the RCBS gauge, but would prefer one that uses the steel balls rather than flat aluminum bars to place the cases on to measure.

Now I do not shoot competition, but just like to know that I have done the most I can do to get a factory rifle and my reloaded ammunition to do the best it can and to be able to place a bullet where it needs to go as long as I do my part. Do I use match or custom brass like Lapua? NO, I use what brass that is commonly available to all us reloaders and use it to make the best ammunition that I can out of it. I have groups usually in the range of 3/8 inch in spread and have had loads go "BUG HOLE" also. These days, the gun is probably better than me, as I do not get so shoot everyday like I used to.

JOHN
 
Quote:
What's runout again?



That's when it's raining or snowing real hard and you have to go out to the driveway to get the newspaper! /ubbthreads/images/graemlins/grin.gif

Seriously, I have no tools for measuring runout, but I read a tip somewhere about bullet seating. The tip suggested that when seating the bullet, do it in three strokes of the press handle and seat the bullet about 1/3 of the way with each stroke. While you do this, you rotate the cartridge in the shell holder about 1/3 or so before each stroke.

Like I said, I don't have a tool to measure, but the last time I loaded for my 7.5X55 K31 I followed the procedure and my groups tightened up noticeabley.
 
yotehunter, I hate to bother you, but is there any chance you could provide a pic of the 2 shellholder trick you use?? do you sit them both top up?? one inserted in the groove on the ram and the second one set on top the first? I might like to give this a try.

one other thing I have doen is to take a bit of lapping compound and place it on a bullet, then chuck the bullet in a drill and place the seating plug on the bullet, and spin the bullet slowly to more acclimate the plug to your choice of bullet type.
 
My technique is, neck sizing with a Lee collet neck sizing die and rotating the case 3 times during the bullet seating step - just as Longcruise described. I'm using military LC brass and the runout is averaging about .003 to .004. Anything that is .005 or greater, I mark and use for fouling shots.

From past experience,I know that these two steps are decreasing the amount of runout I was seeing with a more traditional full length sizing die. When I say more traditional, I'm referring to a expander ball instead of the collet sizer. I also have been using the Lee bullet seater die. I'm not sure if that is helping or not.

Prior to this, I was using the RCBS dies and runout was probably around a .007 or .008 average.
 
Quote Sheldon: I'm using military LC brass and the runout is averaging about .003 to .004. Anything that is .005 or greater, I mark and use for fouling shots.

Sheldon, why not straighten up these casings that have the .005 run out instead of using them for just fouling shots.

It only takes about 15 seconds to do it and they will all be the same.
I took a piece of 3/4" UHMW (like piece of white cutting board) and drilled different size holes for different calibers in it. Now any casing that has a runout of more than .003 I just insert the bullet & neck into the proper hole and a little "tug" and recheck and that's about it - back to .001 or so.

Most casing will straighten up really easy with very little effort.
 
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Coyote control, yes I have considered doing something like what you described. However, my concern was with neck tension. I was afraid that if you simply force the bullet toward the centerline of the bore, the neck tension on that cartridge would be significantly different than the other shells. I'm thinking that the part of the case in contact with the bullet (the neck) will yield and leave the neck more non-uniform - slightly egg shaped.

Now, if you are sizing the holes so the UHMW fits over the neck of the case and forces the neck and bullet into alignment, then the tension of the neck to bullet should be unchanged. I would expect this process to net better results?

Have you done any testing with the shells that you straigtened against the non-straigtened ones? Do you size the holes in the UHMW to fit the bullet or the neck of the cartridge?

I seem to remember a product that did this straigtening process. Has anyone heard of something that corrects bullet runout on loaded rounds?

Sheldon
 
Quote:
yotehunter, I hate to bother you, but is there any chance you could provide a pic of the 2 shellholder trick you use?? do you sit them both top up?? one inserted in the groove on the ram and the second one set on top the first? I might like to give this a try.

one other thing I have doen is to take a bit of lapping compound and place it on a bullet, then chuck the bullet in a drill and place the seating plug on the bullet, and spin the bullet slowly to more acclimate the plug to your choice of bullet type.



I just take 2 shell holders and flip one onto the other and carefully raise the ram up till they touch the seating die exactly in the center. It works, or if you have access to a perfectly machined flat piece of steel, aluminum to use, that will work also. While the ram is raised, then tighten down the lock ring. If you send me an e-mail address, I can send you a pic....JOHN
 
Sheldon,
I use the neck when straighting the bullet. I have never seen any problems with this as far as showing on paper.

I started doing this back when I first got the Neco Concentric guage, that was back in '93 and been doing it this way ever since.

On Mag casings it doesn't take much effort to straighten them, for the necks are short.

I drill the holes in UHMW just so the neck clears just a couple thousands. You could probably do just fine if you wanted to use a 1/2" board of the white stuff instead of 3/4's like I mention above.
 
Thanks guys for all the good thoughts

It's been one of the few techniques discussed here that everyone seems to agree makes a positive difference. I'm surprised Runout hasn't gotten more attention. It appears to make more difference than either neck turning or Distance-off-the-Lands.

The only problem is that other than "Coyote Control's" Bend-It-Back solution and/or buying new more expensive dies, there doesn't seem to be an easy solution on how to keep from getting runout or fixing shells that have it. Though I do like the idea of rotating the shell during the seating of the bullet.


After reading these posts and an article about Runout, I've begun to wonder if there is a correlation between longer length slugs for any one caliber and increased runout.
 
Everything makes a difference.
The only ones you need to worry about are the ones that make a measurable difference for you and your rifle.

Jack
 
I beleive the tool is called the "bersin" tool. Checked into it, and probably will get one, but getting set up for all calibers can be a bit expensive.
 
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Runout???? I thought that was what I did, after I finished stuffing bullets in cases Ive primed and powdered, and was in a rush to get out coyote hunting in the morning!
For "most" guys, minutia like runout, is absolutely inconsiquential.
 


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