Small Pistol Primers vs Small Pistol Magnum Primers 357 Magnum?

Discussion in 'Reloading' started by ncav8tor, Jan 8, 2019.

  1. ncav8tor

    ncav8tor Well-Known Member Benefactor Charter Life Member

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    Does anyone know what kind of velocity hit (fps) one would take by not using small pistol magnum primers and instead just using small pistol primers in 357 Magnum?
     
  2. Apache 4rank

    Apache 4rank Member Sponsor

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    Cant comment on the specific loss in velocity I did notice wildly changing velocities. I find magnum primers are more consistent and more stable.
     
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  3. ncav8tor

    ncav8tor Well-Known Member Benefactor Charter Life Member

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    Thanks for that info.
     
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  4. Catfish

    Catfish E Pluribus Mendacium Charter Member Supporting Member

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    It would depend a lot on which powder you are using
     
  5. Apache 4rank

    Apache 4rank Member Sponsor

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    148g wadcutter
    3g of Bullseye in .357 brass
    This is really a .38 load

    Or

    158g flat point berry's
    5.5g N320

    Feels like a spitball outta my revolvers
     
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  6. ncav8tor

    ncav8tor Well-Known Member Benefactor Charter Life Member

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    For sure, powders all burn at different rates and different temperatures. Local outside air temperature, elevation, etc also play into the mix. I asking in terms of generalities, if there is such a thing.

    Primarily, I was wondering if the manufacturers had published any data or if anyone had done their own tests with different powders to make a somewhat definitive statement on the matter.


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  7. Crazy Carl

    Crazy Carl seriously?

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    Definitely powder dependent. 2400 doesn't require magnum primers & my .41 shot erratically with them. Switched to standard primers & it shot great. For the kinds of loads you'd use, say, Unique or 231 for, magnum primers are definitely not called for. All that changes with slow burning powders & max loads.

    There's a ton of info on the 'net about this very subject, if you go lookin' for it. Just figure out what powder yer gonna use & go to the manufacturer's load data page on their website to see what they recommend.
     
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  8. Bailey Boat

    Bailey Boat Senior Member Charter Member Benefactor

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    I don't give reloading advice or load formula's on this forum any longer. Too many idiots that will argue with a brick wall to waste time on. If you really want to know, give it a try and post results or consult a reputable manual...
     
    Last edited: Jan 9, 2019
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  9. Toprudder

    Toprudder Be vewy vewy qwiet. Supporting Member

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    That jives with a report I read, where 2400 powder reached max pressure with a lower charge, and had a resulting lower velocity when using magnum primers. Max performance was with standard primers.

    Performance differences between regular and magnum primers will be dependent on the powder used.
     
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  10. Slacker

    Slacker Liquor and Whores...

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    Also case capacity. For example:
    I've seen minimum charge weight 38spl loadings show erratic velocities with standard primers, but smooth out with magnums.
    Basically, ya gotta try it and see.
     
    Last edited: Jan 9, 2019
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  11. Ikarus1

    Ikarus1 Avtomat Krishna-kov

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    For Bullseye/TG and just about every other non-magnum (H110/W296) powder, I just use SPPs. It's usually for my cast plinker loads otherwise I'd be shooting full bore H110 powder firebreathing loads with a CCI magnum primer.
     
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  12. ncav8tor

    ncav8tor Well-Known Member Benefactor Charter Life Member

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    I don’t know who the heck this is directed at but if it is me, I am pretty sure that I didn’t ask anyone for any reloading advice.

    For the record, I’ve got a shelf full of reputable reloading manuals.

    Edited for forum decorum.


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    Last edited: Jan 9, 2019
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  13. Catfish

    Catfish E Pluribus Mendacium Charter Member Supporting Member

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    Anecdotally I can tell you:
    1) magnum primers are generally match up with certain powders, not certain cartridges.
    2) Using a standard primer when a magnum is called for can result in poor ignition, incomplete burn, erratic velocity
    3) using a magnum primer when a standard is specified can have any result from no change to unexpected pressure spikes.
    4) SRP is basically equivalent to SPM as long as your gun will set them off.
    5) Whatever you're doing, start low and work up.

    Sorry I can't be definitive but I don't think that's possible outside of a lab.
     
  14. Toprudder

    Toprudder Be vewy vewy qwiet. Supporting Member

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    That pretty much sums it up.
     
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  15. ncav8tor

    ncav8tor Well-Known Member Benefactor Charter Life Member

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    OK, this question was a perplexing one and so I decided to test it out for myself to see what I came up with. I tried to be as exacting as I could be without completely going down a rabbit hole, i.e., I did not weigh and sort every projectile.

    I started with:
    1. brand new virgin Starline 357 brass
    2. 14 grains of Alliant 2400 powder (each round individually weighed on a RCBS Chargemaster Combo)
    3. Because I wasn't using a maximum powder charge, I tested three different types of CCI Primers: CCI small pistol primers, CCI small magnum pistol primers and just for grins CCI small rifle primers.

    My test pistol was a 4 inch Rossi 357 Revolver. My chronograph was a Competition Electronics ProChrono Digital Chronograph with Digital Link to upload the data to my cell phone in a PDF format.

    DISCLAIMER: This is my load data utilizing my components, pistol, chronograph and reloading skills. These are my results and your results might vary. Do not use this loading data or the results as a definitive guide on what you should reload. You alone, are responsible for what YOU reload.

    Here are the results and just for reference, the last chronograph results you will see is for factory Federal 357 158 Gr JSP ammunition.

    Edited to show proper powder charge used in this post. Thanks Crazy Carl!

    IMG_0453.PNG

    IMG_0454.PNG

    IMG_0455.PNG

    IMG_0452.PNG




     

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    Last edited: Jan 9, 2019
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  16. Crazy Carl

    Crazy Carl seriously?

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    24gr of 2400 in a .357?!?!? Will that even fit in the case? I don't even know of a .41 load that calls for that much 2400. Did you mean 14gr?
     
    Last edited: Jan 9, 2019
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  17. Apache 4rank

    Apache 4rank Member Sponsor

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    Very cool. Thank you for this detailed share.
     
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  18. ncav8tor

    ncav8tor Well-Known Member Benefactor Charter Life Member

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    Yeah, I fat fingered that post:eek:! It has been corrected but the chronograph data shown in the photos and pdfs are correct. Thanks CC!
     
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  19. Crazy Carl

    Crazy Carl seriously?

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    Y'know, if I'd paid more attention to your post, I'd have seen the data listed on yer load sheets & not even said anything. Lol!
     
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  20. Skeeter190

    Skeeter190 Life is good! Supporting Member

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    Looks to be a little more than we talked about. Interesting data, I promise I wont use it:p
     
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