Might be mistaken,but I thought the major difference was the cup thickness in the primer.Handguns typically have lighter primer strike. Although I have used SR primers in a .357, but was primarily shooting them in ammo I used in a Rossi Model 92 carbine. They did go bang in my Ruger Security Six and S&W 686 however.
Right now with the AR crowd buying up every SR primer on the shelves I use the SP primers I have.
Based on an article by John Barsness - GUNS magazine pg 26 May 2009. [JB, formerly of Handloader is one of the most qualified gunwriters when it comes to primers and reloading in general]
Information from the Speer #14, Hornady #7, Nosler#6, and Lyman #49 reloading manuals, Alliant and Accurate Arms data.
CUP THICKNESS
Handgun primers have thinner cups than rifle primers, making them easier to ignite with the typically weaker firing pin fall of handguns. Small Pistol primer cups are .017" thick, while Large Pistol primer cups are .020" thick. This is the reason using handgun primers in .22 Hornet rifle loads sometimes results in pierced primers in some guns. Obviously their substitution in the high pressure .223 Remington would not be a good idea.
I don't accept John claim that **all** Small Pistol cups are .017 and that ***all*** Large Pistol cups are .020 thick. This is likely true for some manufacturers, but there's a huge variance in the overall "toughness" of small pistol primers. Some of the European brands, especially S&B are very hard as they are designed for use in both pistols and SMG's. IME, failure's to fire or primers requiring double strikes are much more common with the hard European primers in regular handguns. In Contrast, Winchester primers, or at least the older Winchester's I'm still using on from my Y2K stash, are much softer and with all else being equal, primer ignition problems go away when they are employed.
Since I have a better stock of pistol primers right now, I'll be saving the S&B SP's in the event I need a substitute for SR's.
