357 Mag small pistol or small pistol mag primers

[sbrmike]

I have never used Small Pistol Magnum Primers in my 357 Magnum 158 grain .358" diameter L-SWC loads over 6.0 grains of Unique. Does anyone recommend the magnum primers for this load?

 

[Paul in Nevada]

I would save the magnums for other loads. I doubt you would be over pressure with the magnums since the listed velocity is only 1kfps but obviously you should reduce and work back up when switching components. If that's all you have go for it. Otherwise it's a waste.

 

[WR Moore]

The magnum primers are for hard(er) to ignite powders than Unique. The cups may also have slightly different specs to better withstand high pressures. In 50 odd years of reloading .38/.357 I've only used the magnum primers once, and that was recently, because the load data was developed using them AND, I'd bought 500 of them by mistake.

 

[CH4]

Unique works just fine with both magnum and non-magnum primers.

 

[sbrmike]

Thanks for the replies. I'll stick with Small Pistol Primers.

 

[alwslate]

Most handloading manuals specify magnum primers with all.357 loads due to the tall case and air space with light loads. My chronographing tests show improved consistency with magnum primers with all .357 loads, light to heavy so that's all I use.

 

[Greyman50]

I use SPMP with 2400, SPP with Unique, never problems since 75.

 

[venomballistics]

You could use magnums in it, but there's no logical reason to support it outside availability.

 

[243winxb]

If you get a pierced primer, ever, switch to magnum.

If using 2400 powder, a WSPM primer will require a reduction in 2400 powder.SAAMI PRIMERS | The High Road

 

[oddshooter]

I have often read that the Magnum primers were for slower powders like H110 or 4227.

I have noticed myself that a magnum primer can clean up a dirty load (unburnt grains of powder) some as well.

Prescut

 

[Krogen]

Alliant doesn't recommend magnum primers with Unique in the .357 Magnum. I'd rely on their expertise.

 

[DWalt]

Small Rifle primers will work just as well. Pretty much identical to a SPM primer. I have used SR primers only in all of my .38 Special and .357 loads for many years, and even in several other calibers.

 

[Eddietruett]

I have used Federal magnum SPP exclusively in every 9mm, 38, 357 that I've loaded for the last 5-6 years with Titegroup, Bullseye, Unique, Universal, CFE Pistol, 2400, H110 and Lil Gun. I have seen no noticeable difference except it does help some powders burn cleaner. I've checked loads as light as 2.7gr Bullseye to Max loads with 2400 with a chronograph and saw more difference from gun to gun than I did from Std to Magnum primers. No high pressure signs. Your results may vary but I'll continue to use magnum since that's all I have

 

[ArchAngelCD]

Magnum primers are only needed for powders which are hard to ignite like W296/H110, HS-7, HS-6 and the like. They work better when lit by a magnum primer.

Unfortunately load manuals these days use SPP for .38 Special and other "standard" cartridges while they use SPM primers for anything that has a "magnum" name. I wrote Hodgdon and asked them why and they said they use and list a magnum primer for cartridges like the .357 Magnum because even if the powder doesn't need one because they are concerned some reloaders will not read the primer used and assume a magnum primer is required. That may raise the pressures making the max powder charge no longer within the max pressure limits.

If you have older manuals like the Speer 8 or 9 look at the data for the .38 Special using HS-6/W540 and you will see a magnum primer was used in the load development.

Unique and 2400 are very old powders developed before magnum primer were made. They seem to perform better with a standard primer over a magnum primer. The SD and ES numbers are lower with standard primers so that's what I would use, even with 2400 in the .357 Magnum.

I hope this helps a bit...

 

[alwslate]

Alliant doesn't recommend magnum primers with Unique in the .357 Magnum. I'd rely on their expertise.

The older genuine Alliant and Hercules manuals used Federal 200 primers with all loads and powders, even Bullseye and Red dot. The current published Alliant data isn't the data originally developed by them.

 

[jem102]

I gave up on pistol pistol primers, standard or mag, for my full .357 "magnum" loads years ago and only use Federal 200 Small Rifle.

 

[Eddie Southgate]

I have never used Small Pistol Magnum Primers in my 357 Magnum 158 grain .358" diameter L-SWC loads over 6.0 grains of Unique. Does anyone recommend the magnum primers for this load?

No. No need for mag primers with Unique.

 

[CH4]

You could use magnums in it, but there's no logical reason to support it outside availability.

That's correct

 

[Bill Lear]

Magnum small pistol primers aren't just about explosive material quantity. The most important aspect is primer cup thickness. I would recommend loading .357 magnum loads with magnum primers for the thicker cup...primers are the main weakness of small-primer handgun cartridges because even the magnum versions have thin cups. In fact, if your hammer system can handle it I'd recommend working all loads up using small magnum RIFLE primers to get the super-thick cups that don't flatten out like velum at 36K psi.

 

[antonio_oc]

Go magnum

Literally ALL reload manuals say to use small pistol magnum primers. I only use them and I've been successful with hot loads H110 Hornady XTP 125 and 158 grains projectiles.
You're free to use what you want, but I have a 100% success and still have all my fingers, I'll stick with that.