Dual purpose primers?

Discussion in 'Ammunition & Reloading' started by My 3 sons, Nov 17, 2012.

  1. My 3 sons

    My 3 sons
    Bonney Lake
    Active Member

    Likes Received:
    I know I'm not he brightest bulb in the box when it comes to reloading as I have been at it for only two years. However, I picked up a brick of lage pistol primers from Winchester at Sportsmans Warehouse last week and it said they were for both regular and magnum cartridges. Can this be so?

    I know the diameter is the same but aren't the properties of magnum primers different?

    If it is true that you can use them for either can I use the magnum primes I bought by mistake when I first started loading in my 45acp or colt rounds?
  2. Key-Hay

    North Carolina
    Active Member

    Likes Received:
    I shoot them for 45 ACP with titegroup. Have never had a reason to not use them.

    Just in case no powder drops, most of the Cowboy guys I shoot with use Magnum primers with Titegroup. This is because with 38 Sp a mag primer (most of the time) will push a bullet out the end of a revolver barrel (have personally experienced this).

    With 45 ACP, I don't want to take a chance of a squib. The Winchesters will push a 200 gn LSWC into the barrel but not far enough to let the next round chamber to battery.

    So far out of the last 8000 rounds I've loaded I've only had 1 45 and 1 38 with no powder.
  3. orygun

    West Linn
    Silver Supporter Silver Supporter Bronze Supporter

    Likes Received:
    You didn't say exactly what the primer is, so I'll generalize.
    Just because a round is called a "magnum", it doesn't mean that it requires a magnum primer. I've loaded 41 Mag handgun rounds for 25 years and I've never used a magnum pistol primer even when using H110 or Win296.
    However I recently started using magnum rifle primers in my 30-06 loads and am thrilled with the results. I have reached the same velocity as with standard primers, but with 1 grain less powder.

    If the primers you have don't say they are "Magnum Pistol" primers and just say "Large Pistol", just load up like you have been. If they are "Magnum Pistol" primers and you have been using standard primers, back the powder off a grain (or 2) and work up from there.
  4. jonn5335

    Active Member

    Likes Received:
    Primers make little difference in performance you may have to tweak your powder charge + or - for standard and magnum primers but I use what's on hand or my closest primer supplier I actually just polished off my small magnum primers tonight loading 9mm I go back and forth but see little difference.
  5. deadshot2

    NW Quadrant WA State
    Well-Known Member

    Likes Received:
    People most often misunderstand what a "Magnum" primer is all about.

    The primary reason that there are magnum primers is two-fold. First, they are somewhat "hotter", able to provide more flame to get powders that can be difficult to ignite started. Also, because "Magnum" loads are higher in pressure than standard loads the cup material is more sturdy to prevent "blowout" through the firing pin dent.

    For those that don't use magnum primers in your magnum loads, you probably are using powders that aren't hard to light off or you aren't shooting at extreme cold temps (sub zero).

    I've used magnum primers in regular loads mainly because I had them and not the regular primers. A small adjustment down in powder load and everything worked just fine.

    For those without the experience it's best to follow the recommendations in the published Load Data. Just remember, in time they too will have all the experience of us "Old Pharts".
  6. Darkker

    Mesa, Wa
    Active Member

    Likes Received:
    My Pressure Trace dissagrees with your "higher pressure" theory.
    MOST brands do NOT use thicker cups on their mag primers, Vs their standard primers. And Mil-Spec ALSO DO NOT have thicker cups, they have a different anvil height.

    So what is a mag primer all about? They were originally invented for Roy Weatherby's 75+ grain cases, using very old tech ball powders. IF you think that those powders are still around, and HAVE NOT had any formulation changes; you haven't been paying attention to the propellant world.
  7. ma96782

    Vancouver, WA
    Bronze Supporter Bronze Supporter

    Likes Received:
    The factors of production differ from one mfn to the next. It's hard to "set a rule" about the properties of the various offerings.

    Boxer or Berdan
    Brand A vs Brand B
    Rifle or Pistol
    Large or Small
    Magnum, Standard, Match, Bench Rest or Competition
    Military Spec.

    Some mfns might use a thicker cup material, change the metal alloy or they might heat treat their metal to get the properties they want. Some mfns may choose to change the chemical mixture of the primers. And, as was mentioned, the anvil may also differ. WHATEVER, the combinations can be all over the place.

    I've found that............your reloading manual, the good ones anyway ;), will usually specify which primer brand and they'll spec. magnum or standard or whatever, to use with a certain powder load. Then, (I do it all the time) I may choose to adjust the load + or -, to suit me. And, I've also been known NOT to use the spec. primer suggested in the reloading manual.

    LOL......who really does? So, anyway......

    It's been widely said that certain ball powders and hard to ignite powders, will need a "hotter" primer. And, those shooters that are worried about slam fires might want to use a "military spec. primer" or one with a thicker than standard cup material. Then again........it could be part marketing hype.

    Then.........some modified firearms (i.e. w/lightened firing pins or springs, etc.) may not be able to use a certain brands vs another. There isn't a set rule. But, I've usually found that there are differences (in feeling) when seating various brands of primers and reliability seems to be a factor from one brand to the next. And, I don't have a chronograph but I could also imagine a difference in velocity just from a primer change (not to mention chamber pressure changes). Oh and I forgot......that your firearm's firing pin protrusion, build up of grease and crud, and headspace could also be issues too.

    Oops......btw? How deep are you setting those primers anyway? And, DYK that primers actually vary very slightly in size between mfns?

    So....there are MANY factors at work.

    My Advice is to:

    Experiment a little, log your specs for the loads you use and like. Buy the same products for repeatability (though nothings is perfect). Main thing is.......stay safe and have fun.

    Aloha, Mark

Share This Page