Extreme Spread

Discussion in 'Reloading' started by Austy, Oct 25, 2010.

  1. Austy

    Austy New Member

    Sep 21, 2010
    I was wondering if anyone had any suggestions for reducing the extreme velocity spread when reloading. I am shooting a 7mm STW, using RP Cases, Reloader 25 powder and Fed 215 powders with my current set up. Any suggestions would be greatly appreciated.
  2. 1984nitro

    1984nitro Well-Known Member

    Mar 21, 2010
    I just tested my loads for extreme spread. I did all the case prep that I could trim, annelling, deburr, and uniform primer pocket. worked a good grouping load (1/4") but my extreme spread was 100fps.
    I went back to the bench and tried only sizing the neck about a quarter and went back and got 23fps es. So if you have all the case prep down try playing with sizing depth.
  3. TBass

    TBass Member

    Mar 15, 2009
    I have found that if I apply too much neck tension when I neck size my brass that it can cause erratic velocities.

    I do have some more questions for you

    Are you neck sizing or full length resizing.

    The brass that you are reloading, have they all been reloaded the same amount of times, or are you comparing velocities of rounds that have been reloaded several time to brass that has only been reloaded once.

    Have you confirmed your crony reading to long range targets? I have seen on more than one occasion where the chronology was saying there was a large deviation; however when we inspected the 1000 yard target it became obvious that the chrony was giving bad data
  4. 4xforfun

    4xforfun Well-Known Member

    Oct 1, 2007
    The best ways to reduce ES is with neck tension and seating depth. I am going to assume that all of your brass is from the same mfgr and is the same age. I weight sort mine and do the usual match prep.

    Seating depth......Are you using regular hunting bullets or VLD type, as in Bergers? First thing to look at is what kind of room do you have in your mag/clip....can you actualy get to the lands and still fit in the mag well/clip. I shoot VLD bullets, which like to be jammed into the lands. Be carfull here....to much jam with not much neck tension puts you at risk of sticking a bullet in your chamber should you decide to unchamber a loaded round. The action usually ends up full of powder. I start (with VLD bullets) at full jam....which ends up around .020 - .030 thou INTO the lands. I work my way shorter. If you are shooting regular bullets i would start at about .020 OFF of the lands.

    Neck tension ....If you are worryied about ES and you do not have bushing dies....get them...both a FL and a neck die. As far as which bushings to use....measure the neck diamiter of a couple of loaded rounds....If it's .312 get a .310, bushing 308 bushing and .306 bushing. .314........ .312, .310, and .308. ect... Play with them.

    I recomend shooting your tests at longer ranges...300 yards of more. Shoot everything over a chrono.

    Good luck, and have fun!!!!
  5. TBass

    TBass Member

    Mar 15, 2009
    Building on what was just said, if you jam your bullet too far into the lands it can cause erratic velocities as well... As well as potentially exsessive pressures in some cases
  6. kiwi3006

    kiwi3006 Well-Known Member

    Aug 1, 2007
    I have heard that federal 215 primers will give higher extreme spreads, try changing primer. In my 7mm mag I am going to try the Winchester WLRM next time. I might also try the Federal 210 primer as well.

  7. woods

    woods Well-Known Member

    Jun 4, 2006
    While not perfect, my ES has been reduced dramatically by careful attention to the bullet grip and the interior finish of the necks before seating. Here are the last shots fired over the chrono from various rifles

    338RUM 225 gr TTSX 94 gr RL25 FED215M

    6.5 rem mag 125 NPT 58.5 RL22 FED215M

    280AI 160 AB 60 gr RL25 FED215M

    375 Ruger 260 AB 84.5 gr RL17 FED215M

    30-06 200 gr AB 60 gr RL22 FED215M

    Very seldom do I get an ES of 50 and that will be because of 1 shot that is out of the group. These are all seated off the lands. The AB's around .020" and the TTSX at .050".

    These have .003" bullet grip and the inside of the necks cleaned and polished with Scotchbrite

    and lubed with mica

    along with seating with Competition Seaters and seating variances of .002" or less, sorting bullets by bearing length and measuring each powder charge, it works for me.
  8. coues7

    coues7 Well-Known Member

    Oct 8, 2006
    great info