Fast twist = more pressure?

Discussion in 'Reloading' started by WeiserBucks, Jun 24, 2018.

  1. WeiserBucks

    WeiserBucks Well-Known Member

    Messages:
    1,070
    Joined:
    Aug 16, 2016
    Been loading for my 8 twist 300 Norma. Anytime I even approach normal loads and velocity I'm seeing serious pressure, ruining the brass in 2 firings.

    Could it be twist related ? I've been loading 225 ELD-M's over 81 grains of H1000 safely , getting 2900 fps initially, the same load is now clocking 2940 after 80 rounds fired .

    Never used an 8 twist .30 before and I was expecting to load a little higher charge and get similar velocity to what many others are achieving.
     
  2. Edd

    Edd Well-Known Member

    Messages:
    2,907
    Joined:
    Jan 26, 2011
    According to Bryan Litz, no, it can not be twist related.
     
  3. MagnumManiac

    MagnumManiac Well-Known Member

    Messages:
    1,344
    Joined:
    Feb 25, 2008
    I see that pressure/velocity is not effected by twist rate, BUT I do see a difference with the number of grooves and their width. My 3 groove match barrels in 300WM are faster than my 5R is at the same pressure.

    I have a Remington and a Ruger in 25-06, the Ruger has skinny rifling, the Rem has the wide rifling. The groove number in each is the same which is 6.
    The Ruger is faster than the Rem and shows pressure much later in the data, in fact it surpasses most loading manuals and the pressure trace shows the pressure is where it is supposed to be yet the velocity is higher.

    Cheers.
     
  4. WeiserBucks

    WeiserBucks Well-Known Member

    Messages:
    1,070
    Joined:
    Aug 16, 2016
    Mine is a 26" Bart 5R
     
  5. Swamplord

    Swamplord Well-Known Member

    Messages:
    1,108
    Joined:
    May 2, 2004
    H1000 may be the problem, you need a slower powder that allows up to 100% case fill before seeing pressure, I get that guys want to use H1000 due to it being more temp stable and availability but RL 33 is a much better powder for the 300 and 338 Norma Mags including the various improved cartridges
     
    gohring3006 and HARPERC like this.
  6. tim_w

    tim_w Well-Known Member

    Messages:
    390
    Joined:
    Mar 25, 2008
    Have you tried any other bullets or powder?
     
  7. WeiserBucks

    WeiserBucks Well-Known Member

    Messages:
    1,070
    Joined:
    Aug 16, 2016
    Not yet , I've got Retumbo and 230s ready to test
     
  8. nbowlin

    nbowlin Well-Known Member

    Messages:
    92
    Joined:
    Nov 29, 2011
    Imr 8133 is in the same park with retumbo, RL33 and 570. It takes a little more if it do the same speeds it seems. Which would help with case fill. It’s an enduron powder so it should treat you well with temp.
     
  9. Mike 338

    Mike 338 Well-Known Member

    Messages:
    1,440
    Joined:
    Feb 4, 2012
    Out of curiosity, what action is it in?
     
  10. WeiserBucks

    WeiserBucks Well-Known Member

    Messages:
    1,070
    Joined:
    Aug 16, 2016
    Desert Tech SRS A1
     
  11. Mike 338

    Mike 338 Well-Known Member

    Messages:
    1,440
    Joined:
    Feb 4, 2012
    I had a 338 Norma in a Winchester 70 action that did the same thing. I had to load way down just to prevent pressure issues. I had one smith tell me it was an issue with the bolt. Sent the rifle in to another smith and he said everything was in spec. Never got a firm answer as to what the issue was. It makes me wonder if the brass was defective or to soft. Norma brass is notoriously soft. I ended up buying a new bolt/barrel and turning it into a 300 Win Mag.

    Could be worth the effort of getting 10 cases of a different make and seeing if it helps.
     
  12. WeiserBucks

    WeiserBucks Well-Known Member

    Messages:
    1,070
    Joined:
    Aug 16, 2016
    I'll do you one better, I just received 250 pieces of Peterson brass
     
    HARPERC and Mike 338 like this.
  13. Mike 338

    Mike 338 Well-Known Member

    Messages:
    1,440
    Joined:
    Feb 4, 2012
    Yup, at the time with my 338 Norma, you couldn't find a different brand than Norma. Wish I had waited.
     
  14. WeiserBucks

    WeiserBucks Well-Known Member

    Messages:
    1,070
    Joined:
    Aug 16, 2016
    Hopefully the Peterson brass will allow me to run the speeds I want with the powder I already have. I'm going to load a few this afternoon and see how they hold