Bullet Runout---How to Fix

Discussion in 'Reloading' started by lerch, Jan 25, 2006.

  1. lerch

    lerch <strong>SPONSOR</strong>

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    Well me and BJ just got a SInclair concentricity gauge and their new neck turner. I just ran about 30 of my 25-06 handloads under the gauge and only 4 had less than .003 in runout. Most were around .006.

    How do I remedy this problem, I am currently using RCBS and Hornady dies

    thanks
    steve
     
  2. royinidaho

    royinidaho Writers Guild

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    Yo lerch!

    I solved some of the problem by never full length resizing. But for some reason some cases are just never straight, even with neck turning.

    Used to straighten small engine crank shafts and tried the same process but had poor results.

    So am looking forward to the responses to you post.

    Your runouts seem a bit excessive though.....
     

  3. ss7mm

    ss7mm Writers Guild

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    Steve:

    A search for either “runout” or “concentricity” will get you a ton of reading.

    One thing you can do is take a case before you do anything to it as far as prep goes and measure everything before and after each individual step and this will probably tell you which step in your case prep process is causing the problem.

    With the standard type dies there is always the possibility you may not do better but you can try a lot of things. A lot of problems are caused by standard full length resizing dies. Play with the decapping rod and expander ball to see if you can adjust it slightly up or down and get the unit centered better and possibly decrease runout. Depending on your chamber neck dimensions and your case dimensions you might be able to eliminate the expander ball. The expander ball being pulled through the neck is one of the biggest culprits when it comes to neck runout.

    Make sure all cases are the same length, squared exactly, and that all are deburred and chamfered the same.

    It sounds like, by your description, you are talking about case neck runout before you even get to the seating process. Also, is you measurement before or after you turned the necks? The first thing I’d do is take about 5 or 6 cases as a test group and run them through each of your steps and measure every thing before and after. Find the step that is causing the problem and deal with that step to make it as good as you can. You may end up going with Redding comp dies, or something similar, if you can’t get yours to give you what you want but you should be able to at least determine which step is causing the problem and make it as good as you can with what you have.

    When you get to the seating process you again need to know that all cases are the same length, squared up exactly, and all deburring and chamfering is consistently the same. If it's bullet runout you're talking about, what was the case neck runout before seating the bullets? You can slightly seat the bullet, turn it a little, seat it some more and even turn it again before finally seating it fully. Sometimes this will give you better seated bullet concentricity. Make sure the seating stem is not interfering with, or hitting, the tip of the bullet. You can play with the seating stem by making slight adjustments to try and center it and get better concentricity when seating.

    In the end, the law of averages will probably indicate that you may be better off biting the bullet, so to speak, and going with some quality comp dies. But until you get to that point you can eliminate as much as you can with your standard dies.

    I look at the die thing like I would with most everything else in a precision long range setup from gun to reloading. I doubt that you would try to save a few bucks on building your gun but it seems like a lot of people want to save a few bucks and not go with the best dies available. In the end I think you’ll find the money spent on quality, comp dies will be an investment you will be happy with after all is said and done.

    Roy.....I waited on you this time /ubbthreads/images/graemlins/grin.gif
     
  4. Jimm

    Jimm Writers Guild

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    Hey Steve ,

    What brass ? Although thats part of the equation you need to get away from the old expander ball .

    You don't have to spend a lot of dollars to do this either. Get a Lee collet die for your caliber , use it , you will be amazed ! No lube necessary , runout in the .0005 to .002 range and I have cases that are on their 6th load that are still this way . I use a neco gauge , 3sixbits thought well of them and Abinok uses one as well.

    For the small $ investment required ( 20 bucks I think ) to find out for yourself there is no reason not to. There are many here that shoot at long range and use the Lee collet dies with great sucess .

    I think that the major problem with getting people to try them is the " you get what you pay for " syndrome . I will be the first to admit that I am a subscriber to this school of thought , however there is an additional adage that applies as well. " There are exceptions to every rule" is the one that I thinking about. The Lee dies are " the exception "

    Whichever way you go I wish you good fortune .

    Jim Brown
     
  5. royinidaho

    royinidaho Writers Guild

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    [ QUOTE ]

    Roy.....I waited on you this time /ubbthreads/images/graemlins/grin.gif

    [/ QUOTE ]

    Thanks, I appreciate that.

    I have something called a Bonanza Coax Indicator. I has a V notch that the case head runs in. Don't think much of it but if the chamber is round then its ok.

    All of the runout, when it occurs, is from the base of the neck to the mouth. I haven't been able to attribute any 'fliers' that are caused by runout, though.

    Thanks for the input.
     
  6. uncleB

    uncleB Well-Known Member

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    Lerch,
    A percentage of this (somewhat small) can be caused by neck wall thickness varience. neck turning off the high side helps. A standard seating die can make matters worse. 90% of the problem is in the SIZING process, a standard RCBS or hornady die way oversizes your brass. example: take a fired 270 Win case and measure the neck run it through your RCBS fl die without the expander ball...... .025 smaller check your concentricity guage not bad .001 run out . now put the expander ball back in WOW .001 to .010 run out. this is where bushing dies (redding ,wilson custom come in). minimum sizing on uniform neck thickness brass and treating the expander ball like the mother in law is where the number ZERO is awesome.
    UB
     
  7. green 788

    green 788 Well-Known Member

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    "How do I remedy this problem, I am currently using RCBS and Hornady dies."

    That's easy. Just put ten of the rounds with .003" and less runout into one paper bag, and stick a folded note in there indicating "low runout."

    Then put ten high runout rounds in another paper with a folded note reading "high runout."

    Then have a friend mix up the bags and hand them back to you and head to the range--300 yards if possible.

    Fire one shot from the first bag at one target, then one shot from the second bag at a second target. Alternate back and forth between bags and targets until all twenty shots have been fired. Allow adequate time for the barrel to cool between all shots.

    Observe the targets, paying very close attention to group sizes. Then and only then should you look at the folded notes in the bags. Odds are you won't see enough difference in group size to worry you. But if you do, and it is determined that the high runout is hurting you, then you can begin to take steps to reduce it.

    Dan
     
  8. abinok

    abinok Writers Guild

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    Lerch,
    what caliber we talking about?
     
  9. lerch

    lerch <strong>SPONSOR</strong>

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    I am not OVERLY worried about he runout in my 25-06, it is my mid range coyote and deer gun.

    What I am worried about it in is my 270 AM and another gun project I have in the works. For these guns I want evry peice of ammo I load for it to be the absolute best it can be. So that any mistake that is made I know will be my fault.

    For these guns .003-.008 runout aint gonna cut it.


    thanks
    steve
     
  10. abinok

    abinok Writers Guild

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    Being that Kirby cut the chamber in your 270AM, I doubt there will be any problem with the gun /ubbthreads/images/graemlins/smile.gif Consequently, you just need to focus on not screwing up the fireformed-straight neck while sizing. Have you tried sizing any brass without the expander to see how much constriction is taking place? Not saying that the expander is nessicarily the culprit, but it tends to drag problems to light. What trimmer are you using? Ive seen unsquare case mouths and expanders cause runout problems.
    The "best" solution may well be a lee collet die as Jim mentioned. .001" and under is common on everything I load with them. Naturally, you would have to have a custome one, but,even then, its only $50. Id also suggest that you specify a pair of mandrels that are undersized when you order it. It will come with one thats .0015" or so under bullet diameter. you will probably want one thats .0025, and .0035" under, so you can have more controll over neck tension. Even with the custom mandrels, it should be under $70.
    Give it some thought /ubbthreads/images/graemlins/smile.gif
    Its $70, but it will pretty much whup your runout problems.
     
  11. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Lerch,

    As UncleB already mentioned, the expander stem creates about 85% of all Run out problems in ammo using conventional dies.

    Here are a few tips to try using conventional dies that will help with your run out issues.

    First do as Uncle B stated and try sizing some cases in the FL die with the expander stem removed, it will surpise you!! Generally run outs drop to 0.001" or less instantly. Only problem is these dies reduce the neck diameter to much and require the case necks to be expanded back to the proper dimension.

    First thing is to get the case deprimed without sizing the case. You can do this by dropping the expander/depriming stem as low as possible to deprime the case before it contact the die body, or use a smaller diameter expander stem. Whatever you use, we need the cases deprimed before starting this process.

    Now, with the cases deprimed, and the expander stem installed back in the FL die, adjust the FL die down to size the proper amount on your case, generally I like 2/3 to 3/4 the neck sized when partial full length sizing.

    First thing to do now is to determine how the FL die body is effecting neck run outs. Try sizing some cases. With the die lock ring loose, run a case up to the point that you want it sized to. Lock the die body lock ring down and then withdraw the sized case. This should hold the die in proper alignment.

    Size another case and then measure the neck run out on this case. If it is 0.001" or less, your ready for step 2. If it is not, untighten the die lock ring and repeat the test but with the lock ring loose instead of tightened. SOme die threads are not perfectly true, as are some press threads off a bit. If they are and you tighten the die lock ring down you will pick up run out.

    Run a properly lubed case up into the FL die until the ram is at the top of its travel.

    Then raise(unscrew) the expander stem up until it stops against the inside of the case mouth that is in the die. Then turn the expander back down 1/2 rotation just to give it some breathing room.

    DO NOT tighten the lock ring on the expander stem!!! Very important, let her float!! THis will allow it to self align with the case as it is pulled over the expander ball.

    The benefit here is similiar to a sliding sleeve inline sizing die. The Inside of the case mouth engages the expander ball before the case is released by the die body in the neck area. Basically, the die body is true in most cases, since the case held in position by the die body, the expander stem is required to center itself to the position of the held case mouth. Leaving the stem floating allows it to do this. And generally the finished expanded case neck will have a dramatically lowered neck run out.

    Keys are:

    -Deprime cases without sizing the case
    -Adjust the die body so it is producing good low runouts
    -Leave that expander stem floating so it can self align


    YOu will see a dramatic decrease in your neck run outs using this system with conventional dies.

    The next issue is the conventional seating die. We need neck run outs as true as possible and the case mouths perfectly square and evenly chamfered or bullet runout will increase during the seating process.

    Using conventional seaters, you can expect to see the neck run out value at least doubled in the bullet run out. Point being you need your neck run outs as low as possible for any hope of getting sub 0.003" bullet run outs.

    There is no real good way improve the conventional seating die. Basically, get that brass as square and even in the case mouth as possible, get the neck run outs as low as possible and you get what you get.

    To greatly improve the bullet run out, you really need an inline seating die. Forunately, Forster makes a great inline seater that is very reasonably priced. I think they run about $30 for the more popular chamberings.

    These will really help the run out of finished ammo.

    When using an inline seater you will generally see the same bullet run out as the neck run outs you started with, or in some cases slightly better.

    There are more expensive inline seaters like the Redding Comp dies but they all do the same thing, hold the bullet and case in the same axial alignment while the bullet is seated. This is key to low bullet run outs!!

    Try that set up with your sizing die and I assure you your neck run outs will drop significantly on average.

    You've started down that slippery slope of run out!!! Kind of like getting a chronograph. All was well before you knew the true!!!

    Kirby Allen(50)
     
  12. Tim Behle

    Tim Behle Well-Known Member

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    [ QUOTE ]
    You've started down that slippery slope of run out!!! Kind of like getting a chronograph. All was well before you knew the true!!!

    [/ QUOTE ]

    That has to be one of the most expensive truths, that any of us will ever learn!
     
  13. Mysticplayer

    Mysticplayer Writers Guild

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    Two very simple solution to your problem: collet or bushing neck sizing. Problem solved.

    however, measure the runout on the fired case just to make sure the chamber isn't out of round.

    I use the Lee collet die whenever it is available and simply love it. You can buy them indivdually or just get Lee to make you a custom set.

    Jerry
     
  14. I SHOOT STUFF

    I SHOOT STUFF Member

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    oKAY. wHAT IS BULLET RUNOUT, AND WHAT IS NECK TURNING?

    Question from an amature reloader.