How can I minimize bullet runout?

Discussion in 'Reloading' started by KQguy, Apr 3, 2008.

  1. KQguy

    KQguy Well-Known Member

    Dec 7, 2007
    I am loading 240gr SMK for my 300 win. mag,and I am not getting very good bullet runout readings.Some of them are as much as .006'' out.All my case necks are good,I don't use any with more than .0015" runout.I am using a Redding competition bullet seater,and an RCBS press.Are there any tricks to getting better bullet runout?
    Also,I am neck turning all of my cases,and using a Redding Type S resizing die with a bushing .001" smaller than the neck diameter on a loaded round(just as Redding reccomends).
  2. Darrell Holland

    Darrell Holland SPONSOR

    Feb 22, 2007
    Concentricity issues

    Greetings, the simplest way to correct the problem is buy a better press. I suspect the alignment of the ram to die is askew. I use the Forrester Co-Ax press and get FANTASTIC results each and everytime I reload. Their press, unlike others, allows the die to float and self-center when sizing and seating bullets. Best buy is from Graff & Sons, you'll need to buy their lock rings for your dies they come in a package of 12, just replace your jam screw rings and start loading near perfect ammuntion.

    I made the change 12 years ago and have NEVER looked back, best kept secret in the handloading market place...

    Keep turning the case necks, just a simple clean-up will do...

    Good luck,

    Darrell Holland

  3. KQguy

    KQguy Well-Known Member

    Dec 7, 2007
    Is there any way to check and make sure the problem is in my press,before I buy a different one?
  4. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

    Jun 12, 2004
    There are several ways to help limit your bullet run out. First thing you need to understand is what is causing your bullet run out from the beginning and in most cases its not when you seat your bullets.

    Need to go back to the beginning. First off, virgin brass in general is not the best for getting very low, consistant bullet run outs. You need good brass and you need to fireform it in most cases.

    After you fire a case, be careful when you eject the case by controling it as its pulled out of the chamber by your off hand. Take that case, run the fired case your concentricity guage. It should run very true, less then 1/2 thou run out or you have some issues with your chamber.

    Once you prove that your chamber is good concentricity wise, now its time to start the process of loading your case.

    What I do to check my FL die, if that is what your using, is to pull the expander stem out of the die. Screw the die into the press down to the point you want. Now DO NOT tighten the lock ring down on the die. Again, DO NOT lock the die in place. Will explain why in a bit.

    Lube your case, run it up into the die to resize it and then clean it off and check for neck run out. There should really be no neck run out if your dies are in good shape and generally they are.

    This tells you your dies are true. So why not lock the lock ring down. well, your press and your dies are mass produced items, as such there are variables in the machining that will result in a non concentric condition if the die is locked down into the press. This is because all those imperfections in the machining will then be transposed into your case and you will see more neck run outs.

    Leaving the die loose will allow the die to self center if you will as you run the case up into the die and generally the neck run outs will be MUCH less using this method. If your worried about the case changing position in the press, take a black marker and make a reference mark on the die and press and you can visually watch to make sure the die does not rotate in the press as you size your cases.

    So now you know your chamber is true and your die body is true. Next step and the one that generally causes the most problems with bullet run out in finished ammo is the expander stem.

    If you now reinstall your expander stem into your set up die and run one of your sized cases through the die again, you will, about 80% of the time see that the neck run out inceases with the expender stem in the press, why?

    Well, its because the case is unsupported when the expander button is passing though the case neck and it can be allowed to move in whatever direction it wants. This can range from just a bit of run out to as much as 7 to 8 thou in run out in the worst cases I have seen. So how do we fix this.

    This will add a couple steps to your loading process using conventional dies but it will be worth it in the end as far as consistant ammo.

    First thing you need to do is deprime your cases. You can either do this using a piece of steel spring wire and your shell holder on the work bench with a small mallet to tap out the primer or you can get a smaller diameter expander button so it will not touch your case neck when you pull the case out. You can also use one of the universal depriming dies as well.

    Once you have all your cases deprimed however you choose to do it, There is a rather simple way to set up your die, WITH the expander button to produce much lower neck run outs in your sized case.

    Take a fired case, clean and lube it. With your FL die in the location you want, Untightened, and the expander stem in the die at its conventional location, run your case up into the die. Leave the ram at its top position with the case in the die body. Now back out your expander stem as far as possible. If your using RCBS dies, this will work very well, if your using Redding or others with a different design, it will not work AS well.

    Anyway, back off your expander until you feel it stop against the bottom if your case neck inside the case, then turn it back down a 1/2 turn so that there is some clearance between the case and neck with the case is in its top position in the die. Leave the expander loose!!!

    Now, lower the case out of the die and you will nearly instantly feel the expander engage the neck of the case, before it has even been released by the neck of the die.

    So what does this do for us. Well, we have proven that the die body is true already. AS such, we use that die body to control the case neck as we expand the case. As the expander passes through the case neck, the die is controlling the case neck for nearly all the length that it is being expanded. This will generally GREATLY reduce your neck run outs.

    Neck run out is critical because whatever neck run out you have, this will be transposed into bullet run out in finished ammo. If your using a conventional seating die, generally you will see the neck run out often double when bullet run out is measured. This means if you are running 1 thou in neck run out, its not uncommon to see 2 thou in bullet run out in finished ammo.

    My goal is to get all my sized cases ready to load with neck run outs of less then 1 thou. THey are not all to this level using conventional loading dies but with the system discribed above, most are.

    With seating bullets, there is no real way to make a conventional seating die perform better.

    In my opinion, its much better to get an in-line bullet seating die such as those from Forster or Redding. These dies have a sliding sleeve that controls the case as the bullet is being seated into the case neck. This greatly decreases bullet run out in finished ammo. I again leave these dies loose in the press.

    With an in-line die, in most cases, the bullet run out will be basically the same as neck run out in the sized cases you started with. In some cases, it will actually be less then the neck run out, WHY?

    Well, if the case necks are inconsistant in thickness, when you expand them with an expander button, the inside of the case mouth may be concentric but the variation in the neck thickness will be transposed to the OD of the case so your neck run outs will read higher then the ID neck run out. This is a good thing! That is why the bullet run out is often less.

    If you want to correct this, take a very light neck turning cut to true up the case neck thickness or get better quality brass to start with.

    These are the steps I use when using conventional FL die to size cases to get the best neck run out possible. For best bullet run outs, you really need a quality seating die. The Forster dies are not terribly expensive and well worth the cost. THe Redding Comp dies are much more spendy, very good but spendy.

    If your using a Redding FL die, the steps discribed above will not work AS well but generally, Redding dies produce lower neck run out numbers anyway compared to other FL dies.

    If your using Hornady dies, at least the newer ones, these methods will not work because then have an expander stem design that needs to be rigid to work.

    Many will say using a neck bushing die will solve the problem. My answer to this is yes and no. If your using an S-type die, you can still get high neck run outs because the case is not controled by the die as the neck is sized. You do not have the expander stem issues but you can still get neck run out issues.

    I have also had customers spend $200 on a full set of Redding Comp dies only to complain their bullet run outs are higher then they expected them to be. Why?

    Well, with a neck bushing die, any imperfection in neck thickness is transposed from the OD of the case neck to the ID of the case neck. When you seat a bullet, the bullet will be guided by the ID of the case neck and as such, will result in higher bullet run outs.

    If your using a neck bushing die, it is always recommended to either use the a brand of brass with consistant neck thicknesses or to take a very light truing pass with a neck turner to even up the case neck. That way, the OD and ID of the case neck are running the same run out value and your finished ammo will be much better quality.

    Hope some of this can be of some help.

    Kirby Allen(50)
  5. britz

    britz Well-Known Member

    Mar 11, 2007
    WOW, good reading from Kirby ;)
  6. Winchester 69

    Winchester 69 Well-Known Member

    Mar 29, 2007
    It would appear that your problem lies in the seating process; the sized brass is not a problem.

    You are using a good seating die, so there is a tweak needed somewhere. My guess would be interference between the bullet tip and the seating plug. Mark the bullet tip with an ink marker and see where two mate. The plug can be drilled if the tip is interfering. Some polish the plug with compound and the bullet to fit.

    The other possibility I woukd ask about is the inside of the cartridge neck. It should be cleaned with a brush prior to the seating process. Also, chamfer the inside of the neck with a VLD (low angle) tool to assist the bullet's getting started straight.
    Last edited: Apr 3, 2008
  7. JeffVN

    JeffVN Well-Known Member

    Mar 19, 2004
    I feel your pain.

    Kirby give lots of good info, so I'll not repeat a bunch of it. Two things:

    The RCBS Rockchucker Supreme (newer press in the last 5 years) is an excellent single stage press. If I can load ammo with a average runout at about 1 thou runout, so can you.

    One trick that you might try with your current press is to start seating the bullet (as in about 1/4 to 1/3 of the full seating depth), then rotate the cartridge with the now partially seated bullet on the shellholder 90 degrees or more then finish the seating process. I've used this technique with some success when I was really struggling with runout.

    Another thing about my loading process is that it seems to be VERY dependent upon my setting the bullet as close to perfectly verticle on the mouth of the case as possible; sounds obvious I know, but when I get sloppy or tired, my runout goes up.

  8. boomtube

    boomtube Well-Known Member

    Oct 8, 2007
    I have read that many people are getting less than perfect necks from the Redding button dies. Seems the buttons aren't always held rigidly so maybe they slide just a bit to one side or other under the forces of sizing. ??? I don't know, but it sounds plausible.

    Most bullet misalignment rises from bent necks and most of that comes from poorly aligned expanders with conventional size dies. I've used Kirby's methods for years, ever since I got my first set of Forster BR dies in which the expander ball can be adjusted to anywhere we need it to be. Kirby is right in that many other dies can also be adjusted to do the same thing. If you do it that way get yourself a universal decapping die and use it instead of the FL die's decapper. But, there is another way to expand that I like even better.

    Getting seating started square is a real problem area, especially so with flat based bullets. For my FL sizing, I have removed most of my expanders and use a Lyman "M" expander, mostly intended for cast bullets, instead. First, it pushes IN rather than pulling OUT on the sized necks and that leaves the necks measureably straighter. Importantly, it also expands the mouth of cases just a slight bit over bullet diameter which allows me to actually set the bullet IN the mouth, not just balanced on top and hoping it will enter correctly. I love the M dies!

    IF you wish to neck size only, the only way to fly is Lee's Collet Neck Sizer die, IMHO. As it comes, it works the brass minimually, won't deflect the neck at all and needs no lube. I have lathe modified my Lee neck sizing collets by cutting a short taper into the split-fingered mouth section, about .030" deep and about a 35 degree angle. Thus modified, they will leave a slight "M" type flair on the case mouth for easy bullet entry. I think it would be easy to grind the same kind of taper with a Dremel tool and grinding point.

    While it is certainly possible that some bullet meplats could bottom in a conventional seater stem, and that could be easily corrected by drilling the cup deeper, there is another problem with most of them. They usually are a sloppy fit in the dies bullet chamber so there is little support for centering the undersized stem until the bullet is significantly off line. In my experiments, using a concentricty gage, the "seat part way and turn to complete" does little because the stem is largely unsupported in the critical area of the die. The only cure for this poor fit is to lathe turn a new stem that snuggly fits the die. OR, you can use the full-chamber seaters made by Forster and Redding, which you are already doing. Given that excellant seater, I think your problem is with bent case necks and no press or other seater can fix that.

    Good luck!
    Last edited: Apr 4, 2008
  9. KQguy

    KQguy Well-Known Member

    Dec 7, 2007
    I am seating my bullets on cases with very low runout(I check them before I seat the bullets).I called Redding the other day,and they told me this happens from time to time,sometimes they have to make special seater stems for people,because of some bullets.Sometimes they change the degrees,or other thigs that need to be done to make the stem work for a particular bullet.
  10. overbore

    overbore Well-Known Member

    Oct 14, 2004

    I completely agree with your free floating/ alignment concept and use "O" rings to allow alignment movement. Any experience with this? You gave a great input; well done and thanks. Cordially, Overbore
  11. KQguy

    KQguy Well-Known Member

    Dec 7, 2007
    I second that,you just gave out some great info.,thanks for the help!
  12. steve4102

    steve4102 Well-Known Member

    Mar 13, 2005
    Very good advice indeed, thanks. I have been chasing RO for awhile now and I have a couple of ways I have reduced it.

    In cartridges where standard FL and Seating dies are the only ones available (9.3x62), I use Kirby's method along with a universal decapping die. It works very well and the price is right.

    In other more popular cartridges where there are many different types of dies available I use the Lee Collet Die followed by a Redding Body Die or Bushing Die for sizing. The Lee Collet Die is a great die for producing very concentric brass. Follow it with a Redding body die and you have an FL sized piece of brass with very very little runout. My choice for seating dies is the Forster BR seater. It works great and is fairly inexpensive.

    I also have a several Forster BR FL dies sets. For a simple two die set these are the best I have ever used. Only two dies, size it and seat it and the concentricity is simply outstanding.
  13. woods

    woods Well-Known Member

    Jun 4, 2006
    Is there a particular reason why no one mentions the RCBS Competition or Gold Medal Match seaters?


    I hear talk of expanding neck mouths in order to set the bullet in the neck to get a straight start on seating and the RCBS seaters solve this. You put the bullet in the side and it drops into a collet that holds it straight and there is a collet that fits on the case to align it with the bullet. I have a couple of Redding Competition Seaters in calibers that I can not get the RCBS Competition Seaters in, but other than that it is the RCBS all the way. And believe me, I monitor runout and mostly solve it Like Steve with the Lee Collets and Redding Body Dies. Then finish it off with the Bersin Tool.
  14. davewilson

    davewilson Well-Known Member

    Feb 19, 2004
    i'm convinced that 90% of getting straight ammo is having straight cases to put the bullet into. i ordered a one piece FL die from Forster with the neck at the size I wanted. it makes perfect brass. for really straight brass i think this is a better tool than a bushing die.the down side is, i don't have any flexibility on the diameter. then i use a 15 dollar generic seater and get very straight ammo. the only thing i do that hasn't been mentioned is to run the brass into the die several times, rotating it between each stroke on the sizing operation. same as when seating the bullet. i also like to hold the brass in the die for at least a couple of seconds while at the end of stoke position. like i said, the trick to making straight ammo is to make straight cases.