Controlling and adjusting runout - concentricity

[Martyk]

What methods do you use to control runout when seating long rifle bullets? One trick I learned was to get the bullet started and seat it about half way then rotate the case 180 degrees and finish seating. Even with this method I still get some bullets that don't seat straight.

I was thinking about getting a competition seating die, but I'm not sure that will really help.

Anyone use the NECO Cartridge Alignment Tool? http://www.neconos.com/shop/?cart=237249&cat=28

 

[Walkalong]

I have a Neco tool. Works great, as do others. Don't get too wrapped up in numbers. If they shoot well is the only real test.

A competition seater by Forster or Redding will seat bullets better than most average seaters. The in line seaters by Wilson or Niel Jones are also great.

Your sizer is the first place to look. If the case is not concentric, you can't seat a bullet straight.

 

[USSR]

Your sizer is the first place to look. If the case is not concentric, you can't seat a bullet straight.

+1. Quality dies go a long ways towards reducing runout.

Don

 

[Bart B.]

People who've measured case neck's for their alignment with the case axis in all stages (new, fired, sized any way) have learned that if the neck's not straight with the case to start with, no seater of any type will make it straight after the bullet's seated.

And there's about 4 different ways to measure runout; each one will get different results with the same loaded round.

Redding's got a good article on this: http://www.redding-reloading.com/techlinepages/concentricity.htm

One big problem in concentricity is those darned neck bending balls (more often called expander balls). They bend case necks after the die's sized them down. If you can use a Redding "S" Full Bushing die with a bushing 1 or 2 thousandths smaller than loaded round neck diameter, most of the neck bending stuff goes away. If the case neck's very straight after sizing, a conventional seater will seat bullets just as straight as an in-line seater.

This aside, if your chamber's straight with the bore axis, 30 caliber bullets with up to 3/1000ths runout will shoot 1/4th MOA at 100 yards. Even with perfectly straight ammo with perfect concentricity, the bullet's still going to be a bit crooked when the round's chambered as well as when it's fired.

 

[Historian]

IMO Forster makes the best seating die for consistant centricity. I love mine and it really works. Results on the range prove it.

Historian

 

[USSR]

One big problem in concentricity is those darned neck bending balls (more often called expander balls). They bend case necks after the die's sized them down. If you can use a Redding "S" Full Bushing die with a bushing 1 or 2 thousandths smaller than loaded round neck diameter, most of the neck bending stuff goes away.

+1. My case necks never have a nasty expander pulled thru them.

Don

 

[Marlinreloader]

Well I do a couple of things mentioned above because I cannot afford those special dies. One, I do what you do by turning the case 180 then running it back through. However, first I size with the expander in then resize with it out. I know it is an extra step but I reload as a hobby as well so I'm never in a hurry and just enjoy the process.

Marlinreloader

 

[Martyk]

However, first I size with the expander in then resize with it out.

So..... what kind of difference have you noticed doing it that way? Hmmmm?

 

[USSR]

first I size with the expander in then resize with it out.

If you're using standard (non-bushing) FL dies, then you will get excessive neck tension, to say nothing about overworking your brass. The way standard FL dies work is, first, the neck is reduced to a very small diameter, and second, the expander ball open up the neck to the proper diameter.

Don

 

[Walkalong]

Yep...

You can get good accuracy using ball expanders, you just are not going to get that guilt edged accuracy one can get using bushing dies or dies lapped out to fit a certain brass/chamber set up.

 

[Bart B.]

All of my RCBS 30 caliber expander balls measured .307" when new. I got a bunch of .31 caliber expander balls then polished them down to sizes .3076" to .3090" in .0002" steps. This works wonders with a regular full length sizing die to get .30 caliber case neck tension good for different neck wall thicknesses and 30 caliber bullet diameters from .3070" up to .3092". Cleaning out the powder fouling with a bore brush before sizing helps keep the necks pretty straight.

 

[Martyk]

However, first I size with the expander in then resize with it out

So in this method, using a standard die, the neck would be to small after running it down again... ??

accuracy one can get using bushing dies or dies lapped out to fit a certain brass/chamber set up.

Walkalong .. who are some of the suppliers of the bushing dies? Are you talking about Redding or Forster?

 

[Ol` Joe]

first I size with the expander in then resize with it out.

With some brass I do just the opposite, size without the expander then with the expander just in the die I push the ball through the neck and withdraw it. Decapping is done prior to cleaning and sizing with a universal decapping die.

This method reduces runout in troublesome brass to less then 0.001" in most and 0.002" in all cases. The little runout still present is from the neck wall variation that will always be present unless the necks are turned. That has its own set of problems to work with.

You may still see some runout in a loaded round due to the same case wall variation. Normally it is very minor, 0.001"-0.003". Any cartridge that shows more then this I toss after fireing. My take is the case is always going to show runout without turning and I don`t feel it`s needed for anything but benchrest quality rifles, and their chambers.

 

[Marlinreloader]

Ol joe

sorry guy's,

I am doing the same as Ol'joe explained, which he explained correctly. I also universal deprime all my brass first, then this process like O'l joe and will sometimes use a universal lee expander die if they are too tight.

 

[Walkalong]

Walkalong .. who are some of the suppliers of the bushing dies? Are you talking about Redding or Forster?

Redding makes some nice bushing dies, as does Forster & RCBS. Redding & RCBS both offer their bushing die in a neck only or a FL sizing die. Wilson and Niel Jones make hand dies that use bushings. You need an Arbor press for the hand dies. You will also need some bushings for the sizer dies. I used a Niel Jones seater for my 6PPC Bench gun with bushings to fit my loaded rounds diameter. I used a threaded custom sizer with carbide bushings to bump the shoulder and body ever so slightly, and size the neck. (And yes Old Joe, I turned my case necks to the nearest .0001 with a K&M neck turner)

Any of the three standard threaded sizers mentioned will do a fine job. (Redding, Forster, RCBS)

 

[Horsemany]

One thing I've done to see improvements with all dies is use a stack of dimes to ensure the die is in line with the ram. The nut does not hold the die perfectly verticle because it contacts the press unevenly due to the threads of the die body. To overcome this I reset the die body. I thread in the die where I want it. Then loosen the lock ring of the die. Now I raise the ram with a stack of dimes or extra shellholder on top so I make contact with the bottom of the die. When you touch the die you will see it stand up in perfect alignment with the ram. Holding light tension on it now tighten the lock ring and you're done. I've seen improvements in run out and I do it on the sizer and seating dies.

 

[Walkalong]

I have always run the case up into the die a little bit as I tighten it down to help center the die in the threads. The stack of dimes is a good idea.

The Forster Co-Ax press has that problem licked with its "floating" die set up.

I used one of the small aluminum specialty presses (Watsons I think, been a while) for my 6PPC loads for my bench gun. (Similar to this Sinclair press)

 

[kelbro]

For those that must make do with what they have, here's another way to reduce runout. Run the case up into the die past the expander and loosen the locknut on the expander stem. Pull the case back down and when you feel the expander firmly in the neck, tighten down the locknut on the expander stem.

 

[Horsemany]

For those that must make do with what they have, here's another way to reduce runout. Run the case up into the die past the expander and loosen the locknut on the expander stem. Pull the case back down and when you feel the expander firmly in the neck, tighten down the locknut on the expander stem.

Good tip. I'll use that one.

 

[pocketchange]

keeping concentricity

Greetings to a positive group.
On occasion when primer pocket's are getting attended to, a wobbler shows up (wobbler: shell case head that is not perpendicular to the case neck). Living with a little "wobble" is ok but some find the brass bucket rather than getting reloaded.
My observation is that not too many reloaders seem to be concerned with this situation.
Just wondering if my observation is correct?
pc.

 

[Bart B.]

pocketchange asks about case heads not being perpendicular...... Out of square case heads have been a problem for decades. Few people know what they do to accuracy. And some folks don't know that out of square bolt faces are more often the cause of them being out of square in the first place.

When the case is made, it's headstamped near the end of its coin, cup, draw, rim, size and trim operations. The head's fairly square when the case is new. Running it through high speed loading operations doesn't change it much. But when it's fired in most rifles, all that high pressure flattens the case head against the bolt face. The case head now has virtually the same angle perpendicular to the chamber axis as the bolt face has. Service rifles, including those match conditioned to hold 4 inches at 600 yards all day long with new ammo, are notorious for producing about the most out of square case heads. Some of the military teams tried reloading fired match brass to shoot it again, but it was a disaster.

Reloading one of these unsquare head fired cases doesn't square it up. If it happens to index to the same orientation when the bolt's closed on it, it'll shoot very accurat each and every time it's reloaded. Otherwise, groups will open up 1/2 ro 2 MOA depending on how unsquare the bolt face and case head are.

To eliminate this problem, have your bolt's face squared with the chamber axis, never the bolt axis. Few, if any, factory rifles have their bolt's axis in line with the receiver threads for the barrel tenon. Simplest and best way to do this is to put the stripped receiver on a mandrel turning on centers in a lathe, then face off the receiver's front to just clean it up for the barrel's shoulder to fit perfectly to. You'll need a thin spacer to let the barrel clock back into correct alignment and headspace.

 

[ranger335v]

"One trick I learned was to get the bullet started and seat it about half way then rotate the case 180 degrees and finish seating. Even with this method I still get some bullets that don't seat straight."

That's a good trick. ? It will help until you get a concentricity gage! Then for you will find that it does nothing for bullet alignment. Any bullet started half way but off axis will stay that way as it's finished no matter how many times you turn it. In my tested experience....

Key to straight seating is a straight neck AND a seater that doesn't mess it up.

In practice I find that LIGHTLY turning necks, then using any body die to lightly bump shoulders, a Lee collet neck sizer for straight necks with proper tension and finishing with a Forster BR or Redding Comp seater provides all the concentricity a factory rifle can benefit from.

As side issues, many neophytes seem to think hot primers and seating precisely at the lands while having charges, bullets, cases weighed out to .000001 gr., and OALs at the ogive exact within 00001", are all essential to good accuracy. Actually, none of them are all that important. Both high bullet tension and hot primers are usually harmfull.

 

[Bart B.]

ranger335v states:

Key to straight seating is a straight neck AND a seater that doesn't mess it up.

Couldn't be stated better.

I ran a test on 60 some fired Winchester .308 cases years ago. All cases had their necks previously turned to a bit over .013 inch before firing. A third were neck only sized in a Neil Jones neck sizing die with a .333 bushing. Another third were full length sized in a standard RCBS die with its neck lapped out to .333 inch; no expander ball used. And the last third sized with a conventional RCBS full length sizing die with a .3080 expander ball.

All the sized cases were spun on a runout tool to check neck runout. Support points were a V at the back on the pressure ring and another V at about midpoint on the shoulder. I was checking runoug on the mean case axis as it would fit the chamber when fired; jammed hard into the chamber shoulder by the firing pin's impact and the back end pressed to the top of the chamber by the extractor.

Largest runout was with full length sized cases and the expander ball. Medium runout was with the neck only sized cases. Smallest runout was with the full length sized cases in the lapped out die.

All 60 cases had Sierra 168's seated to an OAL of 2.8 inches. Half of each die specific group had bullets seated with a conventional RCBS bullet seating die. The other half had their bullets seated with a Wilson chamber type hand bullet seater.

All 60 or so "dummy" rounds were checked for runout. In all instances, the bullets tended to align quite well with the case neck axis. Cases sized with the standard full length sizing die with an expander ball still had crooked bullets. And the straightest seated bullets were in the full length sized cases from the lapped out die. Neck only sized cases with seated bullets still had some runout.

I'm convinced that if you can resize cases and keep their necks straight, you could probably seat bullets quite straight by smacking them with a ball peen hammer.

But they don't have to have "zero" runout to shoot well. Two to three thousandths runout as measured from the shoulder forward to a tenth of an inch back from the bullet tip (.308 Win., for example) will easily shoot 1/4th MOA or better at 100 yards from a good barrel with decent components.

 

[ranger335v]

Bart, your experiments included reamed and bushing dies, dies I don't have but our analysis is the much same.

I have come to LOVE Lee collet necks dies partly because the average "bullet tension" with them is low. And they insure the inner neck is the same, no matter the actual neck thickness (well, within reason anyway).

I'm convienced that too small necks require so much seating force it almost guarantees they will be bent off axis during seating even IF the standard expander ball doesn't pull the necks sideways. I read a LOT of comments that many like to have at least .003" of "tension" but I believe that"s too much for best concentricity! I get best results with .001" and can see some deterioation with .002"!

I put "tension" in quotes because it really isn't tension at all, not as such, it's only an interference fit we measure in thousants. Any neck smaller/tighter than about .002" under bullet diameter simply premanently stretches when the bullets are seated, therefore anything smaller becomes irrelivant. BUT, the additional force required to seat bullets in those smaller necks WILL push - bend - them off center.

I'm certain there are exceptions to anything but I've found that once a neck is bent during seating there is too much slop in most seaters for any "turning half way around" to correct it very much. A full body supporting straight-line seater, a true "comp die", usually aligns the bullet-to-neck during insertion better than any conventional or short-sleeve type seater can. In clear English, that means that I'm not impressed with the Hornady or RCBS "Comp" seaters. IMHO, they are no better than conventional seaters, which are after all quite good for most purposes.

Last observation; some seem to feel that micrometer seater stems are kind of magic for accuracy; they aren't. I like them for ease of use, sometimes, but micro stems don't really do a thing for concentricity/accuracy. They are a nice, but expensive luxery and few of my (Forster) comp seaters are so equipped. I set my seating depth with either a Hornady OAL tool or an RCBS Precision Case Mic so a micro stem is not of much use to me.

 

[USSR]

I get best results with .001"...

+1. Less is more, when it comes to neck tension.

Don