Full length sizing die and neck tension

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  • lrgrendel
    Warrior
    • Jul 2013
    • 662

    Full length sizing die and neck tension

    Was playing around tonight on my reloading bench.

    I have two bolt action rifles in the same caliber, one for hunting and one is for precision.

    I use Hornady brass for the hunting one and LAPUA for the precision.

    Tonight I was experimenting with my FLS die and measuring the neck tension it gave you. The results were interesting. An obvious statement would be that neck wall thickness affects neck tension. The point being I saw 2 very different neck tension measurements from 2 different brass manufacturers.

    Now I also own a Neck Sizing Die where I can control the neck tension with the bushings but for some one with only a FLS Die, the different neck tensions could make a huge difference on accuracy.

    Last point! For the hunting rifle I only full length size, for you hunting purists!
  • Cornbread
    Warrior
    • Dec 2015
    • 288

    #2
    Yes it does. However, with a full length die when you pull the expander ball through it sizes the inside of the neck and pushes the inconsistency to the outside. With a bushing die( if you don't use the expander ball,and most don't) your sizing the outside of the neck and any inconsistencies are pushed inside. This is why you you should turn the necks or use really good brass like Lapua that has consistent neck walls with a bushing die.

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    • lrgrendel
      Warrior
      • Jul 2013
      • 662

      #3
      100% true....

      Comment

      • Effenpig
        Unwashed
        • Nov 2017
        • 9

        #4
        Another factor that affects spring back is "work hardening" when brass has been fired several times.

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        • bfk4lyfe
          Bloodstained
          • Jul 2017
          • 42

          #5
          Is the general consensus to NOT use the expander ball on the bushing dies?

          Comment

          • Sticks
            Chieftain
            • Dec 2016
            • 1922

            #6
            Someone expand on this aspect please.

            Gas guns typically have a dented case mouth from hitting the deflector. I know, you can put a piece of loop side velcro on the deflector to mitigate this somewhat.

            If you don't use the expander, you have a dent that is still there, if not more pronounced since you just pushed it inside.

            Two passes? One with the expander to remove any out of round, second pass to neck size? The Redding Type S die does not give you the option to remove the expander - that is what holds the decapping pin.
            Last edited by Sticks; 12-13-2017, 01:04 PM.
            Sticks

            Catchy sig line here.

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            • FW Conch
              Warrior
              • Nov 2014
              • 289

              #7
              For hunting accuracy...don't sweat neck tension, beyond reasonable solutions.

              For precision...neck turn, along with all the other OCD that goes with it. How much or how little precision can You live with? ;-))

              JMO

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              • Cornbread
                Warrior
                • Dec 2015
                • 288

                #8
                Originally posted by Sticks View Post
                Someone expand on this aspect please.

                Gas guns typically have a dented case mouth from hitting the deflector. I know, you can put a piece of loop side velcro on the deflector to mitigate this somewhat.

                If you don't use the expander, you have a dent that is still there, if not more pronounced since you just pushed it inside.

                Two passes? One with the expander to remove any out of round, second pass to neck size? The Redding Type S die does not give you the option to remove the expander - that is what holds the decapping pin.
                There are a couple ways to do this. You can set up your die with a bushing and use the expander so it just basically straightens the neck and does not work the brass much. Or you can take a regular sizing die backed way out and just push the expander in to straighten the necks. Or use a expander mandrel for neck turning to straighten them.

                Comment

                • bfk4lyfe
                  Bloodstained
                  • Jul 2017
                  • 42

                  #9
                  Originally posted by Cornbread View Post
                  There are a couple ways to do this. You can set up your die with a bushing and use the expander so it just basically straightens the neck and does not work the brass much. Or you can take a regular sizing die backed way out and just push the expander in to straighten the necks. Or use a expander mandrel for neck turning to straighten them.




                  Could you use these as the first stage then run them through a bushing die without the expander ball as the second stage?

                  Comment

                  • Cornbread
                    Warrior
                    • Dec 2015
                    • 288

                    #10
                    Yes. Many bolt guys will use them on new brass to straighten any dents and give more uniform tension as new Lapua can be tight. With a semi where your beating up your necks it can be used then also. Now some cats will use the bushing die and then run them through the mandrel instead of using the expander ball. The theory is that with the bushing you are pushing any inconsistency in the necks inside and pushing the mandrel in will set more uniform tension and move it to the outside without pulling the necks out of line like you can with an expander ball. There is debate on weather this does any good. Especially if your not competing at 1000 yds.

                    Comment

                    • bfk4lyfe
                      Bloodstained
                      • Jul 2017
                      • 42

                      #11
                      Originally posted by Cornbread View Post
                      Yes. Many bolt guys will use them on new brass to straighten any dents and give more uniform tension as new Lapua can be tight. With a semi where your beating up your necks it can be used then also. Now some cats will use the bushing die and then run them through the mandrel instead of using the expander ball. The theory is that with the bushing you are pushing any inconsistency in the necks inside and pushing the mandrel in will set more uniform tension and move it to the outside without pulling the necks out of line like you can with an expander ball. There is debate on weather this does any good. Especially if your not competing at 1000 yds.
                      thx

                      Comment

                      • Klem
                        Chieftain
                        • Aug 2013
                        • 3507

                        #12
                        Originally posted by bfk4lyfe View Post
                        thx
                        Another perspective is that you don't need anything touching the inside of the neck to gain sub MOA. In my case, removing the ball from the die produces group sizes that are no different to before it was removed.

                        A while back I discovered that removing the expander ball on a Forster die with Lapua brass produces concentric necks of .003" neck tension. The die still touches the outside of the neck (only) and that seems good enough to round any slightly dinged necks. Obviously you leave the stem in to pop the old primers out. The neck tension without the ball will depend on a few things like your chamber dimensions and what brass and die you use so you might not get exactly .003". I tried the same with a Hornady die and only get .001".

                        Comment

                        • Mad Charlie
                          Warrior
                          • May 2017
                          • 827

                          #13
                          Lapua cases, over the time I have been using them, have had very consistent case neck walls. For my 7.62/.308 loads I had Forster hone my sizing die (Forster) to a dimension that gave me the "neck tension" that I wanted, while leaving .001 for the expander ball to work on. I "float" my de-priming stem a little so it doesn't pull crooked through the neck. Gives me pretty durn straight ammo. Trick is, different cases can have different wall thickness giving different bullet pull if you don't use the expander ball. Not a real problem as long as you don't mix 'em up, will have to adjust a little bit if you are reaching out though. I don't turn necks for semi's and I want at least .003 neck tension for semi's and .002 for my bolt rifles. My Forster expander is giving me .003 on my Grendel. I haven't checked out how much the die sizes the neck down before the expander ball gets to it, but it pulls through pretty easily with Lapua cases, and they are all I have been using so far.

                          Little story, I have an RCBS die bought in '75 that sizes the neck down .007 before the expander ball gets to it, even with Imperial wax inside the neck it is one sob to pull the expander through, has got to be stretching things out a bit, might fix that one day, but I don't shoot '06 much any more.

                          The mandrel technique is good and a LOT of bolt rifle guys use it, I can't see any reason not to use it for semi's as long as you have enough bullet hold. Personally, I think the combination of honed die and mandrel sized neck is the cats butt when it comes to straight ammo. Next best is floating the stem.

                          I have had poor luck getting straight ammo with my Redding .308 bushing dies, no matter what I tried.

                          I have been using a friends concentricity guage for a few years now, but he has moved a few months ago, so I need to make my own. I just don't want to pay what a good one costs when I have a perfectly good Bridgeport out in my shop. Somehow we never got around to checking runout AFTER a round has been chambered and then extracted on to a soft surface, like a bed or something, The chase for concentricity might be for nothing if the round gets bent while chambering in the AR platform. Have any of you guys ever checked that out?
                          Last edited by Mad Charlie; 12-16-2017, 10:49 AM.

                          Comment

                          • Sticks
                            Chieftain
                            • Dec 2016
                            • 1922

                            #14
                            Kind of a note to the .003 neck tension for autos...

                            I've been trying to sort out some issues, and wanted to run some factory brass and primer. I pulled down some Hornady SST, and some of mine that I have done with the Type S dies and a .288 bushing. There was a significant difference in the tension on pulling the bullet, mine were tighter. I don't wonder if we are going too tight with .003
                            Sticks

                            Catchy sig line here.

                            Comment

                            • Mad Charlie
                              Warrior
                              • May 2017
                              • 827

                              #15
                              This is quite possible, my main concern is holding the bullet tight enough to not move or possibly bend as it goes thru the chambering cycle. Time will tell.

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