1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

.357 mag, use of SP primer rather than SR

Discussion in 'Handloading and Reloading' started by lykoris, Mar 3, 2010.

  1. lykoris

    lykoris Well-Known Member

    I'm just wondering if it's possible as I'm really short on SR primers but have quite a few SP.

    6.5 grains of Vihta N320 on a 158 grain FP with COAL of 1.585"

    I'm thinking N320 is a fast enough powder to use a small pistol rather than small rifle primer ??

    Any thoughts??
  2. Walkalong

    Walkalong Moderator

    No reason at all to use SR primers with anything short of really hot loaded (off the charts) .357 with very slow powders.

    No reason in the world not to use standard pistol primers with all loads in .357 short of full loads with powders like H-110/W-296.

    SP will work like a champ with N320 in .357 Mag.
  3. warnerwh

    warnerwh Well-Known Member

    Walkalong is exactly right. Don't use rifle primers in your .357 cases. Except for the very slowest powders a standard pistol primer is what you use. A rifle primer could cause an over pressure issue depending on the load which could cause damage to the gun and/or you. You won't see any load books using a rifle primer for the .357, at least I've never heard of one.
  4. lykoris

    lykoris Well-Known Member

    thanks for the input, Vihta manual says SR which is what I've followed in the past and hence my question.

    Looks like I'll be using SP from now on, I was a little bit worried I might have some unburnt powder as 6.5 is 1/10th of a grain short of max.

    Thanks again! ;)
  5. Walkalong

    Walkalong Moderator

    I have shot N320, N330, & N340 in .357 cases with 125 & 158 Gr jacketed and plated bullets using standard small pistol primers. Clean as a whistle. No residue, none.

    9.1 Grs of N340 and a plated or jacketed 125 Gr bullet will give around 1300 or so FPS, will be ultra clean, and shoots like a laser for me.

    Still working on 158s.

    This is for reference only. Check manuals, start low, and be safe.
  6. rcmodel

    rcmodel Member in memoriam

    Standard Sm Primers for .357 and faster powder like you are using.

    When you get up to a case full of ball type powder like H-110/WW296 you need SM. Pistol Magnum primer.

    I can't think of any use at all for Sm Rifle in a .357.

  7. RippinSVT

    RippinSVT Well-Known Member

    Some guys use 'em in what they call ".353" Casull, which is like a 70,000psi+ load for use ONLY in certain FA revolvers. I've heard they shoot 200gr bullets at 1800+fps. Wow.

    But no, no SR primers for .357mag.
  8. ArchAngelCD

    ArchAngelCD Well-Known Member

    Because you are probably using data for the .357 MAXIMUM instead of the .357 Magnum. I just checked the Lapua site for current Vihtavuori load data. The .357 Magnum data lists a Small Pistol Primer and the .357 Maximum data lists a Small Rifle Primer. Go back and look again and check your charge weights... You will be very high on your pressures IF the Vihtavuori load data follows European CIP pressure limits and not American SAAMI limits.

    .357 Magnum
    Test barrel: 175 mm (7”), 1 in 18½” twist
    Primers: Small Pistol
    Cases: Remington, trim-to length 32,60 mm (1.283”)

    .357 Maximum
    Test barrel: 300 mm (12”), 1 in 18½” twist
    Primers: Small Rifle
    Cases: Remington, trim-to length 40,60 mm (1.598”)
  9. Walkalong

    Walkalong Moderator

    Excellent point ArchAngelCD, and it certainly needs to be double checked. The 08 & 09 Vihtavuori PDF's do indeed list SP for .357 MAg & SR for .357 Maximum.

    If he is looking at the older Vihtavuori PDF's, or the Vihtavuori 1995 Second Edition hard copy manual I have, they list a small rifle primer with .357 Mag loads as well as .357 Maximim.

Share This Page