Small pistol primer for .357 magnum

Very few powders require a magnum primer. Use magnum primers when the data calls for them, otherwise use regular primers.

Maybe (maybe) the slowest powders for .357 might benefit from a magnum primer, H110 or so. I've never measured a difference, and you certainly don't need them for Ram Zip.

I don't use magnum primers in my .357mag loads with 2400 or Trail Boss because the load books used standard primers. And my loads run just fine. If SP mag primers were all I had, I would not hesitate to use those either, in these times.

Good luck.

I find 4227 works better with magnum primers.

Do you have anything slower than zip it's kinda fast for 357....

Yep, the powder dictates the primer; standard or magnum and not what it says on the barrel. When I was using H110/W296 I used magnum primers and now my only use is with WC 820 although I don't think for sure if it's necessary.

gunlaw said:

I find 4227 works better with magnum primers.

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I've found the opposite... but that might change with case fill. Actually... that's a really good question.

Stefan A said:

No, I am just beginning and that's all I have.

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Dont try and achieve any type of hot load with that powder. You may find that you can get very good accuracy. Fast powders work good and often are very accurate (see also bullseye and tightgroup) but have a very narrow loading range with low velocity compared to others. If ramshot is the company available to you trying for siloette or enforcer will give you much higher velocity at lower peak pressure. I load a lot of siloette in 9mm and 45acp.

Hodgdson's Trail Boss data uses small pistol magnum primers.

I guess the temperature of the ammunition could play a roll in the answer to this question?

Many of the companies publishing pressure tested reloading data use the same primer for all of their recipes of a given cartridge. Substituting components can affect the overall results (pressure, velocity, etc). In the case of substituting a standard primer for a magnum one, you will generally get a bit lower pressure and velocity. Work up your load as usual and you shouldn't experience any problems using a standard primer with Zip in the 357 Mag.

JohnB-40 said:

Hodgdson's Trail Boss data uses small pistol magnum primers.

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Hmmm. If that is the case, they changed their guidance. Their original directions did not call for magnum pistol primers.

I have tested some Trailboss pistol loads over a CHRONY with magnum primers and, IIRC, they added ~50fps.

Perhaps that explains the guidance change, as many max'd Trailboss loads could use a bit more velocity.

None of the Trailboss that I have fired has ever needed a magnum primer.

sort of related. but I've found that magnum primers seem to perform better with the really fine ball powders like HS6 and W296/H110 Although I will admit that I needed a chrono to actually tell the difference. Other than the cases being somewhat cleaner with mag primers.

I've notice a change over the years. Manuals used to insist that H110 be use ONLY with magnum primers in .357. Now it's more of a suggestion. I stick with it though.

I loaded some light .38spl rounds and was having trouble with ignition because the powder was spread out in the case. If I tilted the gun upward before each shot it would ignite fine. If I tilted it downward before shooting I'd get inconsistent and light shots. Solved the problem with magnum primers. Gives a little more and hotter ignition.