Neck Concentricity Help

Discussion in 'Reloading' started by esshup, Aug 11, 2008.

  1. esshup

    esshup Well-Known Member

    Messages:
    608
    Joined:
    Mar 23, 2008
    The run-out in the .257 Wby is back (or it never left this particular die).

    The die is a RCBS Neck Sizing Die (not FL resizer)

    If I leave the expander ball in the die, I get .004+" run-out. If I take the ball out, the run-out is .001" to .0015".

    From what I can measure, a fired but not sized neck I.D. is .259/.260 from the Vanguard. With the sizing ball in, the I.D. measures .255. With the ball out, the I.D. measures .249.

    This is NOT a bushing neck sizing die, so I cannot vary the amount of squeeze that is put on the case neck.

    Is the I.D. of the neck too small for seating bullets without the ball expander in the die?

    If so, what amount of interference fit should I be looking for between the neck and the bullet? I have a .25/06 Lee collet die that I changed to work for the Wby., but since I have two .257 Wby rifles, and I know that the chambers are different, I don't think I will get the best results using the same neck sizing die for both guns.

    FWIW, the fired cases from the Mark V measure .255"/.2555" I.D., and the fired cases from the Vanguard won't allow the bolt to close when put in the Mark V chamber before resizing.

    I don't mind buying a bushing neck die, but with a 30+ day wait, I'd really like to get this problem solved this week!

    I tried lightly coating the neck with Imperial inside and outside, and also tried mica inside. All the cases are tumbled before they see the die (even the new ones).

    Suggestions/tips/hints???
     
  2. Winchester 69

    Winchester 69 Well-Known Member

    Messages:
    430
    Joined:
    Mar 29, 2007
    How does the collet die know for which gun it is sizing the brass?

    Actually, the collet die is sizing to fit the brass to a bullet, not a chamber. Use it for both guns and see what your results are.

    Also, you can measure the run-out on the sizing stem for the RCBS neck-sizing die. It may benefit from straightening. Further, if you can leave the sizing stem/expander ball loose in the die, it will find its own center rather than deforming the brass.

    You have several options.
    .
     

  3. Blacktail2

    Blacktail2 Well-Known Member

    Messages:
    91
    Joined:
    Mar 26, 2006
    +1 on leaving the decaping stem loose so it can find center,also try polishing the expander ball a little.To polish the expander ball just chuck the decaping stem up in a drill and use some light emery cloth on it as you spin it. GOOD LUCK
     
  4. esshup

    esshup Well-Known Member

    Messages:
    608
    Joined:
    Mar 23, 2008
    Thanks guys. I'll try both of the suggestions and report the results tonight.
     
  5. esshup

    esshup Well-Known Member

    Messages:
    608
    Joined:
    Mar 23, 2008
    O.K., here's what I did, and the results:

    Polished the expander ball, and left the stem loose in the threaded insert that threads into the die body. Lubed new brass that has .001 run-out and neck sized. .006" run-out. Tried tightening up the threaded insert, and left the lock nut loose. Sized another new piece of brass, same result. (well, .005")

    Rotated the shell holder from the opening @ 8:00 to 4:30. Sized another new piece of brass with the stem lock nut loose. .002" run-out. Tried rotating the shell holder to different clock positions, and got between .004" to .006" run-out, with the exception of the opening @ 11:00. Then the run-out is back to .002.

    I cleaned between all the mating pieces, and no change (it wasn't dirty, but you never know.....)

    I tried loosening the lock-nut on the die body and letting that float in the press along with the expander ball stem float in the die body - .003" run-out.

    These are total run-out numbers - the complete movement of the pointer on the concentricity gauge.

    I give up! Suggestions??

    Update:
    AAAARRRGGG!!!!! I called RCBS and Brian there said: "If you're reloading, I don't think you can get better than .003" total run-out. You can send the press back so we can check the ram to die body alignment if you want." I didn't have the heart to say he was full of.....

    I'm about to order a new shellholder and bushing neck sizer. What size bushings should I order?
    Loaded round neck O.D. is .282"

    I don't have time to send the stuff back, but I doubt that the press is the problem because when I load the .300 Win Mag I can get .001" TIR.......
     
    Last edited: Aug 12, 2008
  6. Buffalobob

    Buffalobob Writers Guild

    Messages:
    5,085
    Joined:
    Jun 12, 2001
    Is your shell holder floating?

    Secondly, try loosening up the lock ring on your neck sizer and then lock it back down trying to not let it torque the die. If that doesn't work then turn the die about a quarter turn and lock the ring down again. Sometimes it is the act of locking the ring that will move it off. One one die I had to push on the die while tightening down the ring. Once I got it right I then locked that ring in real hard so I wouldn't have to do that again.
     
    Last edited: Aug 12, 2008
  7. davewilson

    davewilson Well-Known Member

    Messages:
    2,634
    Joined:
    Feb 19, 2004
    the best fix is to find a good friend that has a lathe. have him chuck up the die so it's spinning centered on the chamber, preferably on both ends of the chamber cavity, not the outside of the die body. now just take off enough metal from the neck to make it, i would say .254. now you don't need an expander ball and the necks will come out VERY straight.

    also, when you size the brass, do it in several steps. just run it in the die a little at a time and spin it a third or half a turn between each sizing.
     
  8. Winchester 69

    Winchester 69 Well-Known Member

    Messages:
    430
    Joined:
    Mar 29, 2007
    How does the measurement w/o the expander ball vary when you rotate the die?

    One scenario points to the expander ball/stem, and the other suggests it's the die.

    You might experiment further using a split lock ring and/or a rubber O-ring under the lock ring. Different shellholder?
    .
     
  9. esshup

    esshup Well-Known Member

    Messages:
    608
    Joined:
    Mar 23, 2008
    I've come to the conclusion that it's the expander, and here's why. Please correct me if my thinking is flawed!

    I have neck sized .300 Win Mag using the same shell holder and can hold .001"-.0015" TIR, so that leads me to think that it's not the shellholder. I can neck size in the .257 die without the expander ball and get .001"-.0015" TIR. I take that same cartridge, force the expander die into it, (liberally coating the inside of the neck with Imperial) and get the familiar .006" TIR. I can partially neck size the brass, rotating it slightly every time I run the brass deeper into the die, but measuring after the final pass still nets me .004" - .006 TIR. Fired brass runs .001" TIR from both guns, both Weatherby and Norma Brass.

    I can rotate the shellholder at all "hour" positions on a clock face, neck size with the expander ball out and get .001"-.0015" TIR.

    I ordered a new shellholder, "S" type bushing neck sizing die, and .280 thru .284 bushings today. They should be delivered Thursday. I'll fireform via COW the brass that I boogered up to get it straight for the new die. I'll bet I have over 50 pieces of virgin brass to fireform tomorrow.:( I wonder how Kirby's PK brake will like COW?:D

    BB: The shellholder is held pretty tightly with the c-clip ring, and it won't rotate unless I turn it manually.

    Guys, your insight into this problem has helped greatly - THANKS from the bottom of my heart. I have learned some new things fighting with this problem, and I will file the info away. I'll let you know how things pan out with the new die.
     
  10. Buffalobob

    Buffalobob Writers Guild

    Messages:
    5,085
    Joined:
    Jun 12, 2001
    Take the C-clip off. Use a rubber O ring to keep it lightly in place. This will allow it to float with the case.
     
  11. esshup

    esshup Well-Known Member

    Messages:
    608
    Joined:
    Mar 23, 2008
    BB: Will do. Thanks
     
  12. Robbin

    Robbin Well-Known Member

    Messages:
    170
    Joined:
    Aug 5, 2008
    I hate to say it, but I would buy another die. Get a redding bushing die. I rarely ever get more that .001 of run out in any of the 5 guns I use them on. With the right bushing, you can remove the expander ball, get lighter uniform neck tension and remove most of the run out. I also use a Bersin ammo fixing tool. I can take a round with .002 down to point .0005 in about 30 seconds. I run every round I reload thru it except my step sons 300RUM, it's too big. I ingnore anything .001 or less and I fix anything that is greater than .001.
     
    Last edited: Aug 13, 2008
  13. drags

    drags Well-Known Member

    Messages:
    134
    Joined:
    Dec 27, 2003
    I take the expander assembly out and size the case then I use a lyman m-die to open up the neck. This usually cuts the run out in half.
    Drags
     
  14. esshup

    esshup Well-Known Member

    Messages:
    608
    Joined:
    Mar 23, 2008
    The bushing die came Friday, and it seems to have solved the problem. My question is: Do I have to use the expander ball that came with it if I punch out the primers before I neck size?

    It also came with an expander ball that is way too small - I'm guessing that it's to protect the collet that holds the pin if I'm not using the expander ball to open up the necks. The instructions didn't mention the 2nd, undersized expander ball.