[ARCHIVED THREAD] - 357 Mag Primer differences

Posted: 12/12/2014 12:47:33 PM EDT

I have a old Speer manual that shows using CCI 500 or 550 for 357 Mag loads. That is standard SPP and mag pistol primer. How much difference will the be with identical powder, load, bullet between the 2 primers? Has anyone tested the difference?

thanks Cmax

Posted: 12/12/2014 2:55:59 PM EDT

[#1]

Depends on the powder used.

The slow burning ball powders need a magnum primer. (W-296, H-110)

It's a good practice to follow loading data as to primer type used.

Posted: 12/12/2014 3:28:29 PM EDT

[#2]

Quote History

Quoted:
Depends on the powder used.

The slow burning ball powders need a magnum primer. (W-296, H-110)

It's a good practice to follow loading data as to primer type used.

View Quote

Those two powders also say 'do not reduce load' for the 125gr JHP.

Posted: 12/12/2014 7:32:29 PM EDT

[#3]

One time (only), I substituted small pistol primers for magnum primers in a W296/158 gr load for 357. What a mistake! There was unburnt powder spewing out everywhere. The non-magnum primer just couldn't get it all lit.

Use magnum primers for full-power 357 loads. <--- Lesson learned.

Posted: 12/12/2014 11:38:26 PM EDT

[#4]

If you can find it, 2400... doesn't need a magnum primer.

Posted: 12/13/2014 12:28:20 AM EDT

[#5]

Mag primers will improve the performance of some powders like HS-6 and 4756, giving them a more complete burn and more consistent speeds.

They will do no good with small charges of fast powder.

The Win WSPM is a great substitute for the Fed 550.

[ARCHIVED THREAD] - 357 Mag Primer differences

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[ARCHIVED THREAD] - 357 Mag Primer differences

[ARCHIVED THREAD] - 357 Mag Primer differences