need help with run out and neck tension

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • cst
    Warrior
    • Jan 2014
    • 239

    need help with run out and neck tension

    I finally ran through all my new Hornady brass and started to brass prep. What I noticed is I have a lot of bullet runout compared to shooting new brass.. I am using:
    Redding Bushing S dies with .287 bushing with expander
    Redding Competition seater die.
    123 Scenars
    I havent trimmed the brass yet and I am about to try .288 sized bushing next.

    What I did notice that The new brass are measured at .286 and a loaded round measure .288-289. When I use the .287 bushing the necks are reduced to .286 and has a lot of tension through the expander when I pull the round out. I also noticed a huge velocity change as well...I need to reduce upto .4mils from orginal dope at 600 yards.


    So i dont know what the problems is...too tight of a bushing that reduces the neck too much in one step(there is no neck only sizing dies out) or die issues....i have stripped em both down and examined everything and cleaned it as well...


    BTW...the brass necks are pretty round and undamaged through my rifle..I padded the the ejection ramp but get pretty dented in my wifes rifle even though its padded as well. But conditions still have significatn runout......but not every loaded round is bad though
    any thoughts?
    Last edited by cst; 07-08-2014, 05:20 PM.
  • cst
    Warrior
    • Jan 2014
    • 239

    #2
    My other thought is that a brass that has been thru the ejection process in a semi automatic could be the reason for the measured runout? As I rotate the brass on the guage...there may be a wobble from the brass being warped even though its been fully sized...and not the bullet being off?

    I wish I could size without the expander ball too but with all the dented necks...
    Last edited by cst; 07-08-2014, 06:19 PM.

    Comment

    • wheelguner
      Warrior
      • Oct 2011
      • 407

      #3
      The purpose of a "bushing" type sizing die is to adjust the grip on the bullet by selecting its ID based on measuring loaded rounds using the brass/bullet combination that you plan on using and selecting the correct size bushing. Expander balls are not normally used when neck sizing with bushing dies. The Wilson Neck Sizing Dies, the most widely used, do not have any type of expanding mechanism at at. If you look at the Forster instructions from the link that Drifter included in his post they are for "conventional" dies. In this type of die the neck is sized down smaller than the target ID as the case fully enters the die body and then "expanded" to the target ID as the the case is withdrawn on the reverse stroke. Both methods work but approach the problem differently.

      When I load new cases I run them thru a die that has an expander mandrel that is the same diameter of the mandrel that I use to turn the necks on my 6.5 cal boltgun brass. This makes sure the neck is round Then I check each case with my Wilson Case Gauge:



      This gauge is machined to SAAMI Specs and and tells me the case will chamber and it also shows if the case is too long. I then neck size in a Wilson Neck die with the correct size bushing, seat primers (I use a hand priming tool) add powder and seat in Wilson Seater die..

      Fired brass is sized in a REDDING TYPE S FULL LENGTH BUSHING DIES using the same bushing as used in the Wilson Die:



      This is a full length sizing die (with the expander removed) and is adjusted to bump the shoulder just enough to allow the case to fully enter the case gauge. Then I finish loading as I do with new brass.

      This gives me loaded rounds that have .001-.002 run out measured on a SINCLAIR CONCENTRICITY GAUGE with a Digital Indicator:

      Comment

      • LR1955
        Super Moderator
        • Mar 2011
        • 3355

        #4
        Originally posted by cst View Post
        I finally ran through all my new Hornady brass and started to brass prep. What I noticed is I have a lot of bullet runout compared to shooting new brass.. I am using:
        Redding Bushing S dies with .287 bushing with expander
        Redding Competition seater die.
        123 Scenars
        I havent trimmed the brass yet and I am about to try .288 sized bushing next.

        What I did notice that The new brass are measured at .286 and a loaded round measure .288-289. When I use the .287 bushing the necks are reduced to .286 and has a lot of tension through the expander when I pull the round out. I also noticed a huge velocity change as well...I need to reduce upto .4mils from orginal dope at 600 yards.


        So i dont know what the problems is...too tight of a bushing that reduces the neck too much in one step(there is no neck only sizing dies out) or die issues....i have stripped em both down and examined everything and cleaned it as well...


        BTW...the brass necks are pretty round and undamaged through my rifle..I padded the the ejection ramp but get pretty dented in my wifes rifle even though its padded as well. But conditions still have significatn runout......but not every loaded round is bad though
        any thoughts?
        Is the problem too tight a neck? If so, use a .288 or .289 bushing. I prefer a bushing that is just small enough that I can feel the expander button being pulled back through the neck. I mean I can barely feel it. Or, either of these bushings should be good enough that you may not need an expander button at all.

        Yet you said you have to 'reduce up to .4 mils' your zero at 600 yards. Reducing your elevation needs by a minute and a half at 600 with a Grendel will be almost impossible unless you are using a very inefficient powder and switch to a powder that will give you another 120 or so fps. And, it has nothing to do with bullet run out, cartridge run out, or any other type of run out. Run out means things like your bullets are not being seated into the neck precisely centered. Or your necks aren't concentric with the rest of the brass. Which has nothing to do with elevation.

        Why do you need to bring your elevation down 1 1/2 minutes at 600, anyway? Haven't met anyone with that need before so I ask.

        BTW -- what are your loads and did you chronograph them using a chronograph you know to be reasonably accurate?

        LR55

        Comment

        • cst
          Warrior
          • Jan 2014
          • 239

          #5
          So I just ordered a Sinclair expander/ mandrel. When in the reloading steps do I use it? Brass gets pretty dented after firing. I dont think I can use it at tgst step because neck diamter would be greater than 295.

          if I use it after I neck sized it with the bushing dies to 287....will it expand it too much? I would like to get .002-.003 neck tension

          it would make more sense to expand it first to remove the dents on the neck then size the outside right? ?..but if I do it that way I would have to FL neck size it again

          Comment


          • #6
            Originally posted by wheelguner View Post
            Then I check each case with my Wilson Case Gauge:

            This gauge is machined to SAAMI Specs and and tells me the case will chamber and it also shows if the case is too long.
            Just a minor correction, those gauges are not designed to be a chamber checker. They will show the trim length and headspace. The Wilson website explains this: http://lewilson.com/casegage.html

            Comment

            • cst
              Warrior
              • Jan 2014
              • 239

              #7
              both are the same chambered barrels..every one keep saying about sinclair expander use on new brass..I get that on a bolt gun...what about in a semi? at what stage do i use the expander...after the final full length\neck resize or before?

              Comment

              • LR1955
                Super Moderator
                • Mar 2011
                • 3355

                #8
                Originally posted by cst View Post
                both are the same chambered barrels..every one keep saying about sinclair expander use on new brass..I get that on a bolt gun...what about in a semi? at what stage do i use the expander...after the final full length\neck resize or before?
                CST:

                You do not need a expander mandrel. At least, no one on this forum has ever needed one on Grendel brass of any make or when sizing down 7.62 X 39 brass. A standard or tapered expander button for your decapping pin is fine. Given a choice, use the tapered one.

                Your problem is probably that you are using a neck bushing that is too small. Try a .288 or .289 bushing.

                Use some Dillon spray lube and get some in the necks.

                Put in the .288 bushing and run your fired or unfired brass (doesn't make any difference) through the sizing die with the expander button just like you would size any piece of brass. Then check your neck tension by feel. You know when seating a bullet how much resistance is about right. Even if the necks are dented, sizing them will remove the dents.

                Then put a piece of your sized brass into the chamber and see that it does chamber and extracts easily. If it does, seat a bullet on a piece and check it again in the chamber.

                LR1955

                Comment

                • cst
                  Warrior
                  • Jan 2014
                  • 239

                  #9
                  LR1955...thanks for the tips...I only have a 289 and 287 bushings and I just ordered the 288.(wasnt in stock). Ihave only been using the expander button with the 287s and thats when I noticed excessive runout. The 289 is too loose since thats what a loaded round measures. Like I said i have a mandrel and a 288 coming....i figure I get rid of the expander button and do the expander in a separate step to help any issues with expander induced runout.

                  Comment

                  • LR1955
                    Super Moderator
                    • Mar 2011
                    • 3355

                    #10
                    Originally posted by cst View Post
                    LR1955...thanks for the tips...I only have a 289 and 287 bushings and I just ordered the 288.(wasnt in stock). Ihave only been using the expander button with the 287s and thats when I noticed excessive runout. The 289 is too loose since thats what a loaded round measures. Like I said i have a mandrel and a 288 coming....i figure I get rid of the expander button and do the expander in a separate step to help any issues with expander induced runout.
                    CST:

                    When you run your dented brass into a sizing die with an expander button, the expander button is the first thing to push through the neck and it will push out any dents. It goes through the neck before the neck enters the neck sizing part of the die. Then the brass is pushed into the neck sizing part where it is sized down. When it is pulled out, the expander button opens the necks up again. The expander button is the same size no matter what neck bushing you are using.

                    Just curious about this. You said you had excessive run out. What is the cartridge run out you are getting?

                    You do know that if you seat the bullet half way and turn the brass half a turn around in the shell holder before finishing the seating process, that you can reduce run out pretty significantly?

                    LR55

                    Comment

                    • cst
                      Warrior
                      • Jan 2014
                      • 239

                      #11
                      I've done the half turn and seat trick with no improvement on the runout. The runout could be as much as .006(right decimal places..?)

                      its written in a lot of sites that when a expander button is pulled out it induces more runout in some cases...Besides using a different bushing..i can only assume its the expander.

                      I have never used an expander on any bolt gun ever before...but when the brass gets all dented up..dont have much choice in an ARplatform.

                      Comment

                      • waveslayer
                        Warrior
                        • Jan 2013
                        • 239

                        #12
                        What reloading press are you using? how is it secured to the reloading bench, table, etc?..

                        Comment

                        • LR1955
                          Super Moderator
                          • Mar 2011
                          • 3355

                          #13
                          Originally posted by cst View Post
                          I've done the half turn and seat trick with no improvement on the runout. The runout could be as much as .006(right decimal places..?)

                          its written in a lot of sites that when a expander button is pulled out it induces more runout in some cases...Besides using a different bushing..i can only assume its the expander.

                          I have never used an expander on any bolt gun ever before...but when the brass gets all dented up..dont have much choice in an ARplatform.
                          CST:

                          .006 run out is pretty much meaningless for a semi-automatic gas gun. You are probably inducing more runout when the bullet gets stripped off the magazine and the ogive slams into the feed ramp, then the barrel, before going into the chamber. There is quite a bit of force being exerted on that bullet and brass during the loading process with a semi-automatic rifle.

                          Anyway, do your thing!

                          LR55

                          Comment

                          • stevegun 1

                            #14
                            Originally posted by LR1955 View Post
                            CST:

                            When you run your dented brass into a sizing die with an expander button, the expander button is the first thing to push through the neck and it will push out any dents. It goes through the neck before the neck enters the neck sizing part of the die. Then the brass is pushed into the neck sizing part where it is sized down. When it is pulled out, the expander button opens the necks up again. The expander button is the same size no matter what neck bushing you are using.

                            Just curious about this. You said you had excessive run out. What is the cartridge run out you are getting?

                            You do know that if you seat the bullet half way and turn the brass half a turn around in the shell holder before finishing the seating process, that you can reduce run out pretty significantly?

                            LR55
                            Amen!

                            Comment

                            • Drifter
                              Chieftain
                              • Mar 2011
                              • 1662

                              #15
                              One option might be to prevent the dented cases that you suspect as the problem.

                              On this link, note the info and link in post #6:

                              Finding dents on my ejected case main body (my Satern Spartan home build, see first picture). I don't get this dent on my AA built Entry upper. The middle picture shows lack of denting on neck with my home build, while the third picture is the dented neck from AA Entry. What would cause the dented main body? Will this affect
                              Drifter

                              Comment

                              Working...
                              X