reloading questions about 357 magnum and 38 S&W

[sigfan91]

Do I need to use magnum primers for 357 reloads? What would happen if I use regular small pistol primers?

Can I use 158 gr. 357/358 bullets to reload 38 S&W rounds?

Thanks for all your help.

[JJE]

Regarding 357 magnum and primers: Fast powders (typically used for "light loads", not full-power magnum loads) usually use standard primers. Alliant 2400 is a very popular medium powder that is good for full-power loads and still (usually) uses standard primers. The slow handgun powders that get the very highest velocities in magnum loads often call for magnum primers because standard primers may not be hot enough to ignite the powder consistently.

In some cases where a loading manual calls for magnum primers, they actually tried standard primers and found that powder ignition was inconsistent (resulting in inconsistent terminal performance). In other cases, they may have specified magnum primers without trying standard primers.

To answer your question: Like always, you should follow the loading manual exactly (including primer type). What happens when you substitute a standard primer for a magnum primer? Who knows? Maybe the powder won't ignite and you get a bullet stuck in the barrel. Maybe the powder ignites every time, but burns inconsistently so that your muzzle velocity is inconsistent shot-to-shot. Will your blow your gun up? Probably not, unless one round sticks a bullet in the barrel and then you hit that obstruction with your next bullet.

Regarding 38 S&W: I don't have any 38 S&W guns, but I know that 38 S&W uses a different bullet diameter (larger?) than .357", and it isn't .358", so I don't think you can even use cast bullets made for 38 Spl or 357 Magnum guns. Hopefully, a 38 S&W loader will come along to clarify, but don't our word for it - check a manual!

[AJD]

Do I need to use magnum primers for 357 reloads? What would happen if I use regular small pistol primers?

Can I use 158 gr. 357/358 bullets to reload 38 S&W rounds?

Thanks for all your help.

As mentioned it really depends on the powder being used. However, even some of the slower magnum powders do not necessarily need a magnum primer. I know many reloading manuals actually state that some powders like 2400, actually perform better with a standard. I also know that Accurate Arms uses standard primers for AA#9 in their loading data. I have always seen H110 and Win 296 listed as being used with a magnum primer so it may be advised to use magnum primers with those powders. Regardless of primer selection, when using a slower burning powder for .357 mag loads, you should use a firm roll crimp to make sure you get a complete burn and to prevent the other bullets from moving forward during recoil.

[ojisan]

.38 S&W barrels measure around .362, if you are referring to the round commonly used by the Brits. IE: .38/200.
Yes, you can use .357-.358 bullets but accuracy is not great.