problems loading 7 STW

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by genecole, Jul 5, 2004.

  1. genecole

    genecole Well-Known Member

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    I am having some problems with pressure in my 7 STW. it is a Winchester Laredo. i loaded 150 Scirrocos in new winchester brass FL sized with a new Redding die and a CCI large rifle primer with 79 grains of RL22. the bolt was sticking and primers were cratering or piercing. so i backed down to 77 grains and was still getting cratering and pierced primers. i am going to try some 160 FailSafes and Accurate 3100 next. I had the same pressure problems with a sendero STW with 160 TSX's and RL22 using RCBS dies. I have noticed really high tension on the neck when i am seating the bullet, with both brands of dies and a couple types and brands of bullets. has anyone else had any of these problems or have any suggestions for me to try.
    Thanks,
    Gene Cole III
     
  2. 1894

    1894 Well-Known Member

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    Jan 8, 2004
    Wow!

    quickLOAD predicts 72kpsi for the 79gr and 66kpsi for the 77gr load. This assumes industry standard COL. If you have a COL of nearly 4" you could get it down to 60kpsi for the 77gr load.

    Reccomended SAAMI nominal max pressure is 56,785psi which you appear to have exceeded by over 25% [​IMG]

    Generaly neck tension etc has a much lesser effect than overcharging.....
     
  3. dakor

    dakor Well-Known Member

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    Gene you probably have a hot batch of R-22 that is why it is best to buy it in a 5 lbs keg or make sure they have the same lot # in the 1 pounders. Now you seem a little hot with the 150gr I would start both bullets at 75 grains and work your way up. How far off the lands are you? The closer you are the less powder you can put in the case is what I have found.
     
  4. genecole

    genecole Well-Known Member

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  5. genecole

    genecole Well-Known Member

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    1894,
    I was just wondering what QUICKLOAD predicts for a 160 Moly-Coated Failsafe in front of 70 grains of Accurate XMR 3100.
    Thanks for the help,
    Gene Cole III
     
  6. Guest

    Guest Guest

    Gene,

    Maybe there are a couple of things to look at here.

    The information that dakor pointed out is correct. Alliant has had a couple of runs of Re-22 that are more than just a bit fast. One lot had to be recalled and customers were compensated with a new lot number.

    The information that you are going by from the Alliant website is tested and written for the 150 gr. Sierra Spitzer Boattail bullet, not the 150 gr. Scirocco. The Scirocco is 0.175" longer than the Sierra SBT, so that when they are loaded to the same OAL, the Scirocco creates more pressure since it takes up more space in the case.

    I usually have to check and re-check loads that I find to be interesting on ReloadersNest. The ones that appear to be hot generally are very HOT! It seems like some of the folks that post loads there are still in the juvenile stages of "beer muscles". They want to post the hottest and fastest loads as if it is some sort of competition. On the other hand, I have found loads printed there that come directly from the Lapua and Norma reloading websites, exactly. Someone just copied them over to ReloadersNest and took credit for the load information.

    This is just my opinion but I think that you will be better served by using a Magnum primer with these slow, bulky powders.

    It might be interesting to measure the necks of a few re-sized cases; inside, outside and wall thickness in a couple of different places. Then compare these numbers with measurements from several fired cases. Measure your expander ball as well.

    If I am remembering correctly, the people that I shoot with are using V V N-170, Re-25 and Ramshot Magnum in cases with capacities running in the 95 gr. to 120 gr. with magnum primers.

    Best of luck! Post back.

    [ 07-07-2004: Message edited by: Crispin Goodall ]
     
  7. larrywillis

    larrywillis Well-Known Member

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    Mar 18, 2002
    Gene,
    It sounds like you have a few problems to solve here. Try lightening up the load a little more and stoke it up SLOWLY. Most of this could have been caused by an unusually hot can of powder. I've had this happen before.

    If you are using Redding "S Type" bushing dies, you can control the seating pressure exactly by using the optimum size bushing. Remember, different brands of brass can have very different neck thickness. This doesn't affect pressure much but it sure is important for accuracy.

    Check out our website at www.larrywillis.com and you can see a long list of tech tips and product reviews that will help. Our website describes the cause of most "case sticking" problems.

    - Innovative
     
  8. genecole

    genecole Well-Known Member

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    Thanks for the help guys. I now realize that I didnt take into consideration the increased bearing surface of the scirrocco versus a regular soft point. I got a good deal on some 160 FailSafes at a gunshow the other day and have decided to scrap the scirroccos and try the failsafes. This time i started out only .5 grains higher than starting load in the nosler manual (69 instead of 68.5)I have not shot them yet but will let you know how they work. they changed my dads 7mag from a 2 incher to an MOA gun.
    Thanks,
    Gene Cole III