Causing case neck runout?

[gunsandgunsmithing]

There are always exceptions but I think the most common cause of runout is just moving the brass way more than necessary. I don't use any mandrels nor expander buttons, just a bushing that gives me the neck tension I'm looking for. That's typically .002-.003 smaller than my loaded round.

 

[rlporter507]

EUREKA!!!!!! I figured it out. Its hard to drop things when you are a tinkerer like me lol.
SO there was someone in the replies above (forgive me if I did not mention be name)
They suggested that when I size with a bushing that is way smaller than what it originally is that the stretching of the brass can cause runout as its too much to go from greater to much lesser.

SO I measured the once fired brass neck with micrometer its .295 luckily I bought many Redding steel bushings as it was on sale (for 6.5 cm I have sizes that go from .295 to .281) SO I cleaned the RCBS fl bushing die and popped in the ,294 with the label up. Lubed liberally the case with imperial sizing wax and and first case since the die was so clean was a bit hard to go through so before measuring I decided to do another case same again with lots of lube and this time it was much easier.

SO I measure both cases the first one had .002 then the second was .001 THIS IS AWESOME I FOUND THE REASON FOR RUNOUT! I feel also if the case is well lubricated and it goes easy in the die (not make noise) then the runout is much less.

"down the rabbit hole again" DOES this mean that I have to ( i plan to go down by .oo2) use all the bushings to get to the desired neck tension size??? For example I want to go to .288 then I have to go through 3 bushings just to get to my desired neck tension. OMG. There has to be an easier way to prevent this.
I did anneal the brass so why is it stretching so much thus inducing runout???

I usually wait 24 hours after annealing as the brass neck and shoulder is very soft there after. Should I size right after annealing, will this cause more problems or solve it????

I don't see a mention of what brass your using. Or what your case neck wall consistency is. when your fired case comes out concentric, your chamber has sized the neck on the outside. when you size the neck smaller it should still be concentric on the outside, but if your neck walls are not consistent it will show up on the inside of the neck. then the expander ball drags back thru, now its concentric on the inside and it will show up on the outside of the neck as not being concentric. also it could be the bushing if your brass is consistent. Your concentricity will only be as good as you neck wall consistency. I had the same problem getting my brass to come out with little to no runout and the solution for my set up was a different brand of bushing. I was amazed, from .004 to .0005 in run out with the die still in the press with just changing the bushing. I agree with the post that making my loads as consistent as possible should eliminate the ammo as the problem, gotta be me. also I agree with does it really make a difference on paper?, well depends on what level of accuracy your seeking and what your tests show.
I have 2 concentricity gauges.

 

[JFrank]

I completely disagree with the “throw away the concentricity gauge” responses. After all, without it, where would you be right now? As far as checking each loaded round for run out, that probably isn’t necessary, but to test the various parts of the reloading process it is certainly necessary. Don’t forget a few things, excessive chamber dimensions are bad. Excessive neck sizing is bad. Dies are not perfect and can cause runout. Presses are not perfect and can cause runout. Shell holders are not perfect and can cause runout. Bushings are rarely perfect and can cause runout.

I do check all my ammo for runout before matches mainly to make sure I use the few worst for sighters. In Long Range Benchrest, my goal for 600 yard groups is under 1”. My goal for 1,000 yard groups is under 2”. My rifles are capable of achieving both of these goals. It can’t hurt to check runout and it certainly builds confidence that you have created nearly perfect ammunition. The extremes you go to should be dictated by your accuracy goals.

Dave.

Sound wisdom, great points and noteworthy advice from an accomplished shooter.
Thanks for sharing.

Jim

 

[Murray Brook]

I completely disagree with the “throw away the concentricity gauge” responses. After all, without it, where would you be right now?

Certainly agree with this statement. If not for the gauge how would you know where in your sizing process that the run-out was coming from then be able to take measures to correct it and see if they worked. Once your process is good then the gauge generally gets little use but none the less very useful in finding out what works and what doesn't. JMO

 

[bozo699]

Certainly agree with this statement. If not for the gauge how would you know where in your sizing process that the run-out was coming from then be able to take measures to correct it and see if they worked. Once your process is good then the gauge generally gets little use but none the less very useful in finding out what works and what doesn't. JMO

This is what I was trying to say but I guess I didn’t type it out how I was thinking. Once I have a new rifle up and going I don’t use it much but then again I generally don’t have much runout. At one time I was big on making perfect ammo but I think people spend too much time on it and if your getting ammo with .003 or less runout I don’t think you can shoot the difference. Thats just my opinion and it may be totally wrong.
Wayne

 

[rlporter507]

I spot check one or 2 on every box, sizing and seating bullets. I never know when something might go south, so theres one on each bench.

 

[Chris Edmondson]

I will tell you how to get excellent runout. Use a one piece die made or modified so that the ID of the die's neck is correct for the application. You can get this by ordering a custom die, or lapping out the neck of a factory die. There is a really good article on how to do this and where to buy the tool. I passed it on to a friend and he was able to achieve excellent runout and improved accuracy for a .264 Winchester. Bushing dies do not work well when you need to reduce the diameter of a fired case neck as much as many situations require, but a properly dimensioned one piece die will.

I'd like to check out the article, please send a link when you have a moment. Also interested in a source for custom dies that do the job.

Thanks.

 

[BoydAllen]

I'd like to check out the article, please send a link when you have a moment. Also interested in a source for custom dies that do the job.

Thanks.

Here you go.

Lapping Reloading Dies

In this project I will take you through the steps and method of altering the neck dimension on a standard reloading die. The purpose of this is to maintain neck alignment to the case body for the b…

rickaverill.com

 

[bozo699]

Here you go.

Lapping Reloading Dies

In this project I will take you through the steps and method of altering the neck dimension on a standard reloading die. The purpose of this is to maintain neck alignment to the case body for the b…

rickaverill.com

I remember that article
Wayne

 

[6MMsteve]

good bullets and good barrels will wash concentricity

 

[misser]

Hello Im new to the forum and heard that this site is where there is the most experts in reloading. I really hope that someone on can help with my situation. I have use the "search" and read many of the old posts and it still does not answer.
Basically the title is my issue: case neck runout.

I noticed that my fired cases have 0 to 0.001, the needles barely moves when spun on the RCBS concentricity gauge.
I clean brass then anneal, the next day I run through the Redding type s fl bushing die with exp ball. I have also tried with RCBS matchmaster fl bushing, same bushing but no exp ball only SInclair exp mandrel. I also measure before putting through exp mandrel. All these methods increased my runout to max 0.004. I did not understand why it was increasing the runout. I tried cleaning die, honing the ball, smoothing out the part that sits on the bushing and still no luck.

I thought that it could be possibly my press. I noticed that my table is kind of tilting as it also sits on a carpeted floor. First I checked any movement on the ram and there was nothing. Then I decided to put my shell holder the other direction this way the case sits against the closed part of the shell holder because the other way I feel that the case slightly moves as the press is tilted and the shell holder opening also allows case to move. (i hope you can picture this)

After doing this I did notice some improvement but not totally removing the runout. I am getting 0.003 still increasing runout from fired cases. So after doing this there is a relation to the position of case in the shell holder inducing runout.

I wanted to try removing the spring in the ram that holds the shell holder but I have no idea how to remove also I notice the the shell holder has no movement on the ram so I doubt removing spring will do anything.

I don't understand. Even if I put the press on a very flat table I will still be getting runout. I will first try the press on a flat surface and see if this does any good.

Pls help before I totally destroy my reloading room to make a new table.

are you checking on the brass neck or on the bullet ?

 

[Firearmsunlimited]

One or more of the suggestions by Bill and Boyd are going to probably solve your problem. A couple of thoughts: your press may have some deflection based on what you mounted it to. I mounted mine to a 3/8" plate that is inletted into the top of my bench. Also, as Bill pointed out, let your shell holder float. I replaced the snap clip that came with my press with an O ring.

 

[Firearmsunlimited]

Idk what he’s doing but the key to accuracy is consistency and you can only be consistent f/l sizing the same every time. Eric Cortina proved for FClass accuracy which is less than benchrest but still accurate, he saw no difference in runout up to I believe.008 but I might be wrong on the number but it was a bunch. Neck sizing is old school short range benchrest and even they abandoned that years ago.
Wayne

"Neck sizing is old school short range benchrest and even they abandoned that years ago." No we haven't.

 

[Mark611]

This is a rabbit hole! there are a lot of opinions on how to achieve this goal! but there is also a lot of commonalities in the methods we use, years ago when I started trying to produce precision ammo, I got on the forums asking questions! what I have learned is this! quality brass like LAPUA or ALFA and brass of this caliber is what is needed to start off with IMO, then choosing dies that don't over work your brass! what has worked the best for me is a simple Redding Body die and a LEE Collet die and a match grade seating die, brass prep again folks have their own way of doing things! another rabbit hole! I anneal my brass if it's not already annealed out of the box! turn my necks for my needs, but I anneal every firing nun the less and trim if needed, my brass stays consistent my runout stays 1k or under using these simple tools! as someone else has already mentioned a good barrel! Like a Bartlein, BRUX, Criterion, and spot checking your runout LOL!!! YMMV

 

[bozo699]

"Neck sizing is old school short range benchrest and even they abandoned that years ago." No we haven't.

Maybe you haven’t most have.
Wayne

 

[BoydAllen]

"Neck sizing is old school short range benchrest and even they abandoned that years ago." No we haven't.

Who is we? I know a lot of short range benchrest shooters and it is generally true that they FL size, using dies that are a close fit to their chambers. This would include Hall of Fame members and Record holders.

 

[Dave M.]

Absolutely, only time I take my down is to check a new die. After that it's going back on the shelf above my reloading bench.

Ditto.

 

[Firearmsunlimited]

Who is we? I know a lot of short range benchrest shooters and it is generally true that they FL size, using dies that are a close fit to their chambers. This would include Hall of Fame members and Record holders.

Boyd, you are correct that most of the current benchrest shooter are full length sizing before every reload because we are shooting higher velocities. Years ago most only neck sized and then later on neck sized during the match then full length sized after the match. Some lower velocity shooters are still just neck sizing but the largest segment has gone to full length sizing before every reload.

 

[Mark611]

I full length resize; I just don't use a full-length traditional sizing method! I do it in separate in different sizing methods, I will no longer use a standard full length 1 piece standard or other FL die, they don't work for me!