[roc1]

How important is bullet runout. I have never worried about in all my years of loading and I have heard if you keep it to .002 or under it will make a huge difference. I was wondering if this is true on lots of reloads all different brass and using a powder measure? which tool works best for checking runout and how do you fix the problem on loaded rounds? I guess turning the necks is the best solution for solving this problem correct? my loads have always done the trick but again I am not a benchrest shooter. I am interested to know how much this would help on overall group size?
Thanks
roc1

[bullseye308]

Need a little more ino. Which caliber for one, which rifle, and what distances are you shooting. It can make a difference, but so can a lot of other things.

Also what do your groups look like now?

[Shoney]

What is run-out? It is more correctly called concentricity. As shooters have become more demanding in their search for accuracy, specialized reloading equipment has come into the market. It is well known that bullet run-out, or concentricity, is a major factor in producing accu-rate ammunition.

In years past, the accepted practice for checking of a handloaded round was to roll the cartridge across a flat surface, such as glass, and note any wobble at the bullet’s tip. This was a fast way of culling obviously defective cartridges, but will fail to isolate those with less obvious run-out problems. Add to this the fact that run-out problems can be caused by not just an improperly seated bullet, but by the case itself, and the limitations of this approach become unacceptable.

Today, handloaders have several options that are capable of measuring concentricity to .001" or less. Most operate on some variation of the same principle. A loaded cartridge is mounted in the unit, normally supported by a “V” block arrangement at the case head and bullet ogive. The cartridge is rotated slowly, while a dial indicator bears on the area of the cartridge being checked. Any concentricity problems are not only immediately visible, but measurable on the dial indicator.

One of the first commercial models, which is still readily available and quite popular, was the Forster/Bonanza Co-Ax Indicator. Recent entries in the concentricity gauge market include models by Sinclair International, NECO, and RCBS. Some models, such as the NECO Gauge and RCBS Case Master, are capable of not only measuring bullet run-out, but case neck variation, wall thickness and concentricity as well. Given the accuracy obtainable, particularly from many of today’s bolt action rifles, using a concentricity gauge to get the last bit of accuracy out of handloaded ammunition makes good sense.

[roc1]

Thanks but how do you fix a loaded round?
roc1

[snuffy]

Thanks but how do you fix a loaded round?
roc1

Shoot it!:D Just kidding, there are tools that can BEND the bullet straight, but I don't buy into that method. You're not solving the underlying causes by "fixing it", you're just applying a bandage.

Here's my RCBS case master in action;

http://photos.imageevent.com/jptowns/arrow/websize/P7040054.JPG

http://photos.imageevent.com/jptowns/arrow/websize/P7040055.JPG

In those two pics you can see .002 runnout on that 69 nosler match HP. As Shoney said, it can also check necks;

http://photos.imageevent.com/jptowns/arrow/websize/P7040056.JPG

If you don't have a match chamber, concentricity will not matter much, if at all. A stock factory hunting rifle won't be able to show a difference!

[ranger335v]

"I have heard if you keep it to .002 or under it will make a huge difference"

Weeeell, it depends on how you define "huge". It matters for sure but only up to maybe a 2" group for most rifles and 5 thou run out can hurt that much. Passed that, additional run out doen't much matter because most chamber throats are tight enough to correct the concentricity to that level.

If you have a .5 MOA rifle and you have maybe 5 thou runout, you could get 2 MOA groups and that could be considered huge I suppose. But, if you have 1.5" rifle then the same runout won't amount to much difference. There are a LOT more 1.5 moa rifles than .5 so runout for most rifles isn't all that important.

So, basically, bullet run out is more important with highly accurate rifles than average ones. And the only way to know what your's has is to get a concentricity gage such as Snuffy's or a Sinclair, etc, and check what you now have. If it's good, less than 2 thou, you have no real problem. If it's greater, it will be because of bent necks. Check where in your loading process that's occuring and find a way to correct it as well as possible. It's REALLY difficult to keep R.O. to a thou or less on a whole box of ammo!

[woods]

As you can see in snuffy's pic, he has a total indicated runout (or TIR) of .002 which means the runout is actually 1/2 that, or .001".

Runout on the case neck can be misleading depending upon upon the brass quality and the type of die you are using. If you use a concentricity gauge to measure on the neck on fired and unsized necks then you will have very little to no runout. The reason is that the brass has been ironed to the chamber neck and those are generally very concentric to the rest of the chamber and all the neck thickness variances have been pushed to the inside of the neck.

If you are then using a Lee Collet Neck Sizer or a die with an expander ball the neck thickness variations will be pushed to the outside of the neck and will affect your concentricity readings when the gauge rides over the high and low spots that are now on the outside of the case neck. This runout is not important. It would not matter if you measured .004" of runout on the case neck if that runout was due to the neck thickness variations. What is important is the runout or concentricity on the bullet.

If you are using a bushing type of sizer and do so without the expander (which is what most do, why would you size the case down to a specific bushing size and then re-expand it with an expander? :what:) then you are sizing the outside of the neck to a specific bushing size and pushing all the neck thickness variations to the inside of the neck. That will have a definite effect on your bullet runout. IOW you could have .001" runout on the outside of the case neck and .005" runout on the bullet. Not good.

That is why it is best to outside neck turn to a consistant neck thickness if you are using a bushing die without an expander. With a constant neck thickness you will have close to the same runout on the outside of the case neck and the bullet. However, if you start out with a bad case with a lot of neck thickness variation, outside neck turning will not correct the problem
http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/neckcenter.jpg

There are some tools to reduce runout. I have a Bersin tool that pushes on the bullet
http://img.photobucket.com/albums/v663/bwestfall/RELOADING/DSCN0388.jpg

Hornady has a new concentricity gauge that will allow you to push on the bullet (or neck - not sure)
http://img.photobucket.com/albums/v663/bwestfall/RELOADING/hornadyconcentricitygauge.jpg

and I have seen one made by H & H.

But the best way to combat runout is to buy the best brass you can get (often you don't know how good it is until you get it and measure it :mad:) and chase concentricity enough to get it under control by modifying your sizing and prep procedures. A good competition seating die will not correct runout but it will not add runout.

Does it make a difference? If it is excessive, yes it will make a difference.

IMO and after spending lots of money and a few years chasing runout back into it's ugly little hole, you can solve 80% of all runout problems by sizing with a Lee Collet Neck Sizer. It has a floating mandrel that will not push your neck to the side or jerk it out of alignment like an expander ball and you don't have to worry about outside neck turning like with bushing dies. Get a Redding Body Die for when you need to push the shoulder back and you are set and have not spent much money.

[USSR]

Good post by woods, as always. But, I will respectfully disagree on the need to neck turn brass in order to use a bushing die. My empirical experience in 1,000 yard competition tells me otherwise.

Don

[Dave P]

"If you are then using a Lee Collet Neck Sizer or a die with an expander ball the neck thickness variations will be pushed to the outside of the neck and will affect your concentricity readings when the gauge rides over the high and low spots that are now on the outside of the case neck. This runout is not important. It would not matter if you measured .004" of runout on the case neck if that runout was due to the neck thickness variations. What is important is the runout or concentricity on the bullet."

I have to take exception with this statement. If the case mouth is not centered in the chamber, by definition then the butt end of the bullet is also mis-aligned, which is not good.

I too have spent countless hours worrying about concentricity (with minimal results on the target), but I agree with woods conclusion: Lee necker and body die is one simple solution for most shooters.

[woods]

Good post by woods, as always. But, I will respectfully disagree on the need to neck turn brass in order to use a bushing die. My empirical experience in 1,000 yard competition tells me otherwise.

Don

Then you must be using very consistant neck thickness brass, Don. Stands to reason that if you have brass that has >.002" variance in neck thickness then that will transfer to interior neck runout when size on the outside with a bushing and that will lead to bullet runout. A few years ago I bought a bushing die in 30-06 and had terrible runout (.005" to .010"). That was before I had an outside neck turner. Gave up on that die and eventually moved to the Lee Collets. Well anyway started getting tight necked custom barrels and had to start outside turning so one night it occurred to me to turn some 30-06 brass and try the die again and that helped a lot. The 30-06 brass had a variance of +-.004" which is not all that uncommon for WW.

There is also the possibility that your rifle is a 1000 yard custom and will shoot most anything well.

"If you are then using a Lee Collet Neck Sizer or a die with an expander ball the neck thickness variations will be pushed to the outside of the neck and will affect your concentricity readings when the gauge rides over the high and low spots that are now on the outside of the case neck. This runout is not important. It would not matter if you measured .004" of runout on the case neck if that runout was due to the neck thickness variations. What is important is the runout or concentricity on the bullet."

I have to take exception with this statement. If the case mouth is not centered in the chamber, by definition then the butt end of the bullet is also mis-aligned, which is not good.

I too have spent countless hours worrying about concentricity (with minimal results on the target), but I agree with woods conclusion: Lee necker and body die is one simple solution for most shooters.

Hey Dave, all I was trying to say there was that you can have runout measured on the case neck and have no runout on the bullet because the inside of the case neck is aligned with the case body and is concentric. IOW the inside of the neck is perfect but because of neck thickness variation the outside has measured runout. However in the vast majority of cases where there is a large variance in neck thickness, then there will be a problem with the neck and case body alignment.

[Walkalong]

I agree that the cartridge run out as measured on the bullet, is more important then the case run out. As long as the bullet is aligned with the bore the case can have a spot or two where it isn't.

For my 6 PPC BR rifle I first reamed and then neck turned to the nearest .0001.

Neck turning and/or reaming is not usually needed (IMHO) unless you are running tight necked chambers. Neck sizing with bushings will work fine if the bullet is concentric, regardless of little imperfections in the neck. The best brass with uniform necks certainly goes a long way towards accomplishing this.

Some folks just turn a little off the necks to even up the walls, and that works well, unless you have to take off a great deal to do it. With the better brass, that won't be a problem either.

All this prep is wasted if your barrel, action, and bullets can not make the grade. ;)

[USSR]

Stands to reason that if you have brass that has >.002" variance in neck thickness then that will transfer to interior neck runout when size on the outside with a bushing and that will lead to bullet runout.

Sounds good, but what actually happen is, when the bullet is seated, it acts just like a mandrel, and any variance in interior neck dimensions are transfered back to the outside of the neck. I use a Redding Competition necksizer bushing, and a Redding Body die in 3 different calibers, and bullet runout is not an issue in any of them.

Neck sizing with bushings will work fine if the bullet is concentric, regardless of little imperfections in the neck.

Yep.

Don

[Walkalong]

The other thing is the whole .002 (or whatever) never transfers completely anyway.