My buddy and myself are going to be testing some differnt powders for a good woods carry .357 load in a 4' S&W, and a pair of SP-101's in 3 1/16" and 2 1/4". The powders will be H110, H4227, W296, N110, and N105. The first three call for small magnum pistol, while the VV powders call for small rifle. I thought the only difference between small rifle and small pistol primers was the cup thickness. Would small rifle be a close if not even substitue for small pisol magnum primers? The main reason I ask is I have a ton of small rifle and no small pistol magnum primers. Thanks for any clarification with this!

I've always used small pistol mag primers even with VV powders in my 357 MAG (NOT 357 MAX!!!). I would EXPECT the small pistol mag primer to be similar but maybe slightly cooler/less powerful than the rifle primer. Again, no problem there.

The small rifle primer's thicker cup is reported to occasionally give poor ignition with the lighter strike of a pistol hammer. I accidentally loaded a batch (50) of 38 spl loads in my S&W using small rifle primers and they all fired without a problem.

I'd say if you are determined to use what you have, work up SLOW, and shoot a lot to test reliability. If you have a chronograph, use it and look for signs of poor ignition...high spreads and erratic velocity. Primers are cheap though...what's wrong with spending $25 and getting a case of pistol primers anyway?

pistol primers are a bit thinner but softer material. the ignition from a pistol primer is softer than a rifle primer. using a rifle primer in a revolver may give you some misfires as the striking for the revolver is much less than the striker in a rifle. so far as magnum primer go, personaly I've never found a use for them in pistol loads.

I'd check your load data and ensure that your W powder specs are for .357 mag PISTOL, and not .357 MAX RIFLE. Also, some books will provide load specs in .357 MAG (not max) for a rifle.

Typically the rifle loads are faster because of a longer barrel. And sometimes they're loaded hotter. Or -- possibly, they're loaded with a rifle primer because they're being fired in a rifle.

Primers are significant in working up a load.

I wouldn't use data that specifies "rifle primers" for a pistol load, particularly when you're loading to "collect data" for a pistol, accuracy, performance, etc.

I'm familiar with H110, excellent choice for magnum loads in .357 or .44 mag. ANY moderate to slow burning powder might benefit from a magnum primer, but you need to work up your data.

As noted above, a case of primers is about $25. That's insignificant when you compare it to cost of bullets, powder, brass, and your firearms.

-- Besides, if you loaded w/ rifle primers and got data, would you really want to continue loading with rifle primers for ammo carried in a pistol? Sounds like a lot of work figuring out data that's not very useful.

I had a full case of small rifle primers. No "small rifle." And so I swapped them at the local shop. Gun shows swap stuff too.

I to haven`t used rifle primers in pistol loads. Although they may work fine I can`t really say. The thought that you may have mistakenly looked at 357 MAX data in place of 357 MAG data is possible. I do know the 357 MAX runs at rifle pressures and rifle primers are recommend because of this when loading this cartridge. The 357 magnum when loaded for a rifle also has rifle primers recommended, but for handgun use I`d stay with pistol loads and primers.