How do you straighten runout?

[Gone Ballistic]

I've got a dilema, I really thought I knew a lot about reloading until I got into LRH. Man, how little I really do know! I knnow I neew some help. I have a RCBS guage I purchased to check runout, neck and case wall thickness,etc. I have found cases that are .004-.006 off. Once you have a case that has that much runout, is there a way to straighten it back to .002 or less?
Second question, when using a neck sizer and you need to bump the shoulder back a hair, what do you use to do it without full length resizing? Or can you?
Answers will be greatly appreciated. Thanking all of you in advance,
Gone Ballistic

 

[Mikecr]

You can cull brass by thickness variance(not runout) to head off alot of it.
From there fireforming will put most existing variance inside.
Minimal sizing always helps to keep runout low after firing.

To minimize sizing with shoulder bumps you can use a Redding body die, or custom die. This works fine with rational pressure loads.

 

[rscott5028]

Good brass, press, dies. You can try neck turning to just shave the high points.

Fire form and verify that it comes out your chamber with low runout.

If the neck ID is not concentric. That will transfer to the bullet TIR regardless of how good your seater die is.

Once the bullet seats crooked, straightening is futile. You may as well just shoot it and start over at that point.

-- richard

 

[Gone Ballistic]

I purchased a Redding body die. Do you normally use this die after neck sizing? I am shooting a custom 300 RUM. If I seat back off the L&Gs .001 or .002 I'm way too long for the magazine box, obviously. Just how important for long range accuracy is it to seat this way vs close to SAAMI standards? I don't know if it would be that big of deal being able to shoot on a repeating basis vs accuracy if it is a considerable difference. I have been able to get groups very close using SAAMI standard length to the groups I get seating close to the L&Gs. but not quite as tight. .388 compared to .424. Thisw is going to make a greater difference when shooting 1000+ yards. I wonder if some primer or powder tweaking might make the adjustment?
I really appreciate you guys giving me replys!

 

[Gene]

The neck sizer does just that - it does not set shoulder back. As Mike said, you need a full body die. Once a crooked neck is fired in your chamber, it should come out straight - assuming the chamber was cut straight. This problem usually arises with the sizing die and/or expander ball. The ball will pull neck out of concentricity. I prefer to lightly turn necks, then size with a bushing die. The die neck has to be straight.

Years ago I bought a Bersin tool to straighten necks. I soon sold it. It was simply bending the necks, then firing would straighten it out until I resized in a F/L die with expander ball. Check your concentricity on one case when it comes out of the chamber, again when it comes out of the die. This may give you the answer .

 

[Gone Ballistic]

Thanks for the info. I thought I was fairly close in my thinking, but it's always nice to get reinforcement from someone that knows for sure. Lee doesn't make a collet neck die in 300 RUM and wanted $250 to make me one, which is way too much for me if their is another die out there that will do a good job. I was told that there weren't enough 300 RUM's sold for them to want to go to the expense of setting up tooling for producing mass quantities of the die at this time. It seems to me that if they can custom make one they would have all the tooling done to mass produce them after that. I would bet that if I had them make me one they would probably come out with them in their regular line within six months. That's the way things generally go for me.
Any suggestion on what brand of neck collet die that's currently being produced you guys might recommend?

 

[Michael Eichele]

The only way that I know how to 'straighten' runout is to load the case and fire it. Then you have to figure out how to size them without creating runout in the first place. I use to turn my necks enough to where when they were ran into the die, they came out with .003 neck tension without the use of an expander ball. Another decent way is to use the body die and seperate neck die as has been mentioned. Also, Redding makes FL dies that you can put neck bushings into the die. You can get bushings of various sizes to get the right neck tension. What ever you decide, the fewer stages and the less you have to run something inside the neck the better. Also, I think guys place too much emphasis on runout. Some of the best loads I have ever used had enough runout to make most here cringe. NEVER check the runout on loads that are shooting lights out. You WILL loose sleep at night after that. There is no replacemnt for finding a good load/barrel harmonic node relationship. That said, having minimal runout never hurts accuracy.

 

[SBruce]

There is alot of good info in the above posts for you to ponder on, and sorting by neck thickness does help quite a bit, even with standard dies. Keeping the neck tension at about .002 or a little less seems to help some too, or at least it has for me.

Neco does make a block with different sized holes in it for different calibers. The idea is that if you find a cartridge with over .003 run out on the bullet right in front of the case, you place the bullet into the block (high side up) and gently press down on the case. In effect, bending it back to strait. According to my Sinclair concentricity gauge, it does straighten out some runout, but I have to be carefull of over doing it, because it will go from .004 one way to .004 the other way with too much force.

My great uncle was a benchrester quite some time back, he had some sort of straightener for runout too, but it worked more like an arrow straightener and the cartridge laid between two points and the tool was used to press down on the neck when the high side was up. This particular tool utilized a dial indicator that was included. I don't know much more about it, and he passed away over 15 years ago.?

With the Neco block, I have to put the round back into the concentricity gauge to tell if I did it enough or not enough and go from there.

 

[nheninge]

Just don't buy into the whole "runout correction" theory. Build em' crooked and straighten them out in the end ( ie hornady/neco runout correction) is absolute crap. I guess when we pour a concrete slab for a house we should pour it crooked and hope the finish carpenters are REALLY good!!! Don't put so much emphasis on runout that you forget about the things that really matter....wind reading, transportation maintenance, etc. Excellent advice all.

 

[rscott5028]

I love gadgets. So, I couldn't help myself and bought the Hornady gauge that let's you correct runout.

After giving it the full benefit of the doubt, I've concluded it's a piece of junk.

It's poorly made with lots of slop.

It will sometimes detect TIR and many times it won't even detect .001" runout while my Neco clearly indicates .005".

You can sort of straighten cartridges with it by switching back and forth to the Neco for the actual measurement. But, after messing with a number of batches, it looks to me like those which are made straight shoot well and those that you straighten are are no better than the ones with a lot of runout and may even be worse.

Since I switched from a Lyman T-Mag to the Forster Bonanza Co-ax press I see a lot less runout and sleep much better.

-- richard

 

[Broz]

the Hornady gauge that let's you correct runout.

After giving it the full benefit of the doubt, I've concluded it's a piece of junk.

It's poorly made with lots of slop.

It will sometimes detect TIR and many times it won't even detect .001" runout while my Neco clearly indicates .005".

I had the same experience with one a friend bought. We determined it ain't worth the powder it would take to blow it to H E double hockey sticks.

Jeff

 

[mountainman]

put your fired cases in your trimmer and turn your outside case neck walls down to the same thickness. Make sure you lube the inside of your cases before you resize, should solve your problem. Thats what I do and have no runout problems. Think about this, If you have a runout problem, and you straighten it out by bending the case(shoulder,neck) the bullet is now offcenter of the case pointing at the rifling at an angle, slight but at an angle. Can't help accuracy. When fired, the case will straighten out and if it does before the bullet hits the rifling you gained almost nothing buy straightening the runout and if it doesn't straighten out before the bullet hits the rifling, then the bullet goes into the rifling crooked. Again, cant help accuracy. If your setting your bullets shallow it may not be a problem correcting runout, just a matter of your setter stem doesn't match your bullet point. Correct or different setting stem should help. I have better luck by turning my neck wall to the same thickness before sizing and seem to get more even neck tension through all my cases. Whichever one of my cases has the thinest wall, then thats the case I turn all my necks down to. Yes It will shorten case life,(neck splits) but all my guns shoot real well. Also I should add that I trim cases the same,uniform primerpockets,deburr flash holes, choose cases that weigh close to the same as well as bullets and weigh powder to the 1/10 gr.This works for me.

 

[trailrider121]

TruAngle. Works great for minor run out correction. Good guy to deal with.

http://www.trutool-equipment.com/TruAngle Guide.pdf

 

[Mikecr]

This is an example of why low runout is more desirable that low eccentricity.
The problem with your straightner is that it assumes runout is caused solely by a neck pointing off axis. But there are actually many contributors to RUNOUT elsewhere.

Now if you counter all other contributors by pointing a neck(that might be just fine) in another direction, it could escalate the condition -when the cartridge is chambered.
It reads low on a gauge, but won't chamber so.