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Thread: Question on .357 magnum and standard primers

  1. #1
    Boolit Bub
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    Question on .357 magnum and standard primers

    I am loading up my normal hunting round and I am now out of magnum primers. I use a 158 gr SWC with tightgroup or unique depending on what I have available at the time. Am I going to have a noticeable reduction in fps with my typical load? I am shooting them out of a carbine.
    Thanks.

  2. #2
    Boolit Master Thumbcocker's Avatar
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    I can't speak to velocity for your load but I have never used magnum primers in .357 or .44. FWIW

    Sent from my SM-G960U using Tapatalk
    You'll go far providin' you ain't burnt alive or scalped."

    Will Geer as Bear Claw in "Jeramiah Johnson"

  3. #3
    Boolit Bub
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    I didn't expect really a difference with the powders I am using. Now with my J-words w296 loads I fear that may be a different story.

  4. #4
    Boolit Buddy
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    In my Marlin carbine I use magnum rifle primers with a warm load but not with lead.

  5. #5
    Boolit Buddy
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    I've never used magnum primers, even with heavy loads of 296/110. No unburnt powder.

  6. #6
    Boolit Buddy badguybuster's Avatar
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    I only use magnum primers with Lil Gun and H110.

  7. #7
    Boolit Buddy
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    When it gets cold slow powders lime 296/H110 (same powder) can be hard to lite. I don't think a 357 holds enough powder to create a problem. I also have never used mag primers in 357, 44 mag or hot loaded 45 Colt. I load with 2400 and have shot at -20 F with no problems. Firearm and ammo were outside in truck over night. With the powders you are using I think the differance in velocity will be within your standard deviation. Have fun and don't ginve primers a second thought.
    Steve

  8. #8
    Boolit Buddy
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    You probably shouldn't have been using magnum primers with those powders anyway. I only use them with H110/W296. All other loads that I use call for standard primers.

  9. #9
    Boolit Bub
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    Thanks for all the responses. I appreciate the friendly way members teach around here. Definitely not like that everywhere. Thanks again.

  10. #10
    Boolit Master 358429's Avatar
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    Shoot em up! Should be fine considering you are using faster powders. I'd be curious to know if this change in your loading may cause them to group better or even more interestingly if the group dispersion did not change at all

    Sent from my SM-G930T using Tapatalk

  11. #11
    Boolit Master Thumbcocker's Avatar
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    Yup. Let us know if anything changes.

    Sent from my SM-G960U using Tapatalk
    You'll go far providin' you ain't burnt alive or scalped."

    Will Geer as Bear Claw in "Jeramiah Johnson"

  12. #12
    Curious Caster
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    I have used everything from small pistol magnum primers to small rifle magnum primers in 357mag and never really noticed a difference. Maybe if you're pushing your loads on the ragged edge of disaster it might make a difference... but at that point, just step up to 357max.
    I'm a big fan of data-driven decisions. You want to make me smile, show me a spreadsheet! Extra points for graphs and best-fit predictive equations.

  13. #13
    Boolit Master
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    Magnum primers weren’t developed for cartridges designated as some kind of magnum. Magnum primers are used for powders that are shaped/coated in a way that makes them harder to ignite. There’s no direct correlation between magnum cartridges and magnum primers. Some powders that call for magnum primers are WW296 and H110 (both the same powder). Read your loading manual and use what they call for. You don’t need a magnum primer for most powders.

  14. #14
    Boolit Master
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    just out of old habbit I use mag primers with certain powders such as 296 and 4227, blc2, 2520, 748 and on--most all ball powders
    but I'm wondering with this question you ask. do you work up your loads, starting low and working them up towards max using published load data manual or online from bullet or powder manufacturers. you say unique, it doesn't need a mag primer. but online hodgdon/imr load data calls for magnum primer using titegroup powder in 357mag
    what are you hunting with your 357 mag?
    most of the time when people say "hunting loads" they usually refer to getting close to or maximum potential out of a cartridge. I dont think either of the powders you mention quite do that for 357 mag. in my limited knowledge and opinion some powders that do help max out performance in 357 mag are AA no 9 or 4100/enforcer, h110/296, 4227, 300 mp, 2400 and there are some others.

  15. #15
    Boolit Grand Master


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    Assuming a normal 4"-6" revolver, with H110 you could go up to 1400 fps or so with that bullet. With Unique, you are around 1200 fps with a max load. I have no idea what it would do from a carbine. It is a noticeable difference, yes. If they shoot better, then go for it. If you don't trust H110 or similar with standard primers, then I see no reason not to use Unique.

  16. #16
    Boolit Master

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    There is no need for magnum primers with tite group or unique.

  17. #17
    Boolit Master
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    use the primers the powder manufactures recommend.no need for mag primers with most alliant powders.try 2400 if you want more speed again std primers .ive cronoed some of my loads .165g gc boolit 13.5g = 1550fps 2400 .195g gc =1350fps .125g jhc 16g 2400=1780fps .all fired from my win trapper.

  18. #18
    Boolit Master

    Moonie's Avatar
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    I agree, no need for mag primers until you start using the slow ball powders like W296/H110. 2400 is a great one to use and there is no need for mag primers for it either.

    you can use non mag primers with W296/H110 but as has been mentioned, in cold weather you would want to, I believe Hodgdon recommends mag primers for W296/H110.

  19. #19
    Boolit Buddy nueces5's Avatar
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    Hello, in Argentina the Mag primers have been gone from the shelves for a long time. I think I have been reloading with std primers for about 10 years, and although it shows that it develops its full potential, what it develops is enough for me.
    I have friends who have told me that they prefer to use a faster powder for their 357, instead of W296. Since they have had ignition problems.

  20. #20
    Boolit Master
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    Do you have any small rifle primers? Thought that spm primers were equivalent to sr primers.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check