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Can you use "small rifle" primers in .357 Mag. cartridges? If so, how would you use current reloading tables? I've just come into about 2500 "free" small rifle primers and was hoping I could use them when reloading for my SP. Thanks folks! :)
 

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I know a few guys use SRP's in the .44 Auto-Mag, but can't offer any advice on this. I'll be watching this post for more replies...
 

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Small rifle and small pistol primers are the same diameter but rifle primers are a few thousandths taller. That means if you seat rifle primers in pistol cases, the primer may extend (proud) and drag on the recoil shield. Some cases have deep enough primer pockets where it is not a problem.

The cup in a rifle primer is much thicker and stifer than a pistol primer because it handles more pressure. That means you may not get a deep enough dent for positive primer ignition ... especially if you installed a lighter hammer spring.

The "mix" (impact sensitive mixture) in a standard rifle primer is nearly identical to the mix in a magnum pistol primer so use the reloading data for magnum primers. If you load non-magnum charges, back off the powder charge weight about a grain.
 

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According to George Frost's book "Ammunition Making", there are two common formulations for small rifle primers. The first, what he calls Type IV, is used for both small rifle primer a well as small pistol primers. If the primers you were using had the Type IV mix, then one would expect there to be little to no difference if you substituted one for the other.

However, there is a second recipe for small rifle primers only, which Frost called Type VIII, which is noticably different. It has more lead styphnate initiator, more barium nitrate oxidizer, it has less antimony sulfide fuel, it has less powdered aluminum fuel, and it contains PETN where the Type IV does not. PETN is a high explosive, but is used in primers as a source of heat and energy. My guess is that this is a hotter primer than the Type IV.

There is another difference and that is sensitivity. By design, the rifle primers are less sensitive and might give ignition problems with lightened mainsprings.

It has been not at all uncommon for people to use small rifle primers in place of small pistol primers when loading very high pressure ammo, like .357 Mags for use in Redhawks and Freedom Arms guns, or the .357 Maximum. Start a little low and work back up. If you have access to a chrono, that would help you a lot.
 

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Read in a reloading man to use rifle primers in a 44 mag. They wouldn't seat flush. Stuck out a few thousands. Large pistol primers are shorter but same diameter.
 

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Small rifle and small pistol primers are the same diameter but rifle primers are a few thousandths taller. That means if you seat rifle primers in pistol cases, the primer may extend (proud) and drag on the recoil shield. Some cases have deep enough primer pockets where it is not a problem.

The cup in a rifle primer is much thicker and stifer than a pistol primer because it handles more pressure. That means you may not get a deep enough dent for positive primer ignition ... especially if you installed a lighter hammer spring.

The "mix" (impact sensitive mixture) in a standard rifle primer is nearly identical to the mix in a magnum pistol primer so use the reloading data for magnum primers. If you load non-magnum charges, back off the powder charge weight about a grain.
PLUS ONE......on the thicker metal used to form rifle primers.
 

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I just Measured the Height of a winchester small pistol magnum primer at .119 in the small rifle was a Rem 61/2 and measured .121 in !so if you build them and they don't stop the cylinder from turning ,I guess you are off and rolling! Kevin
 
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