Intuitively there should be a defineable difference between Small Pistol, Magnum Small Pistol and Small Rifle primers. 'Taint necessarily so! After more than 50 years handloading, many thousands of rounds over a chronograph, and somewhere in the Million rounds loaded area, mostly for revolvers, I have made a few observations that I will generalize and share

1) With some propellants you will get higher velocity, and, probably, somewhat higher pressure using a SPM compared tp SP. With most propellants this is not the case. The Magnum primer usually gives wider extreme spreads and higher standard deviation than the standard primer.

2) With most propellants results with the Small Rifle primer will be very similar to what is observed using the SPM with the same charges. Same cartridge and other components of course. ES and SD will usually be lower with the SR than the SPM, all things being equal.

Many years ago I saw a recommendation in either an old Lyman manual, Keith's writings, or Phil Sharpe's book, that .32-20 should always be loaded with SR primers regardless of being shot in a rifle or pistol. I can say that my older Lyman manuals do show SR for .32-20 in the handgun data section. In this long, thin case ignition is noticeably more consistent with the SR compared to SP. The chronograph tells the tale!

Mis-fires with SR primers in revolvers. So long as the revolver is in good mechanical condition, and with factory springs, this is a myth. After shooting many (not just several!) thousand rounds from several S&W and Colt revolvers, I have experienced exactly ZERO Mis-fires in any revolver, over a period of 50 years, when using SR primers in .32-20. Remember, these guns are identical, except for caliber, to their .38/.357 counterparts, so there is absolutely no reason for mis-fires in those calibers either.

Most re-loading lore goes back to the very beginning of re-loading with smokeless powders. There was more lot-to-lot variation in propellants and primers. Later there were so-called Black Powder primers, very mild, corrosive and non-corrosive primers, which all gave different results. There were cases of different internal styles and dimensions. In those days the advice to reduce charges 10% and work up again when changing any component made sense, it really doesn't anymore. This can be demonstrated by the chronograph. There is a tremendous amount of advice in print that falls into the "Sounds good, so it must be right." category, but it isn't. There have been many like Keith, Casull, Weatherby, Newton, Dr. Mann, and hundreds of others who were willing to experiment and determine what the limits really were. If it weren't for their kind we would still be shooting round ball guns with Flint ignition and Black powder!

I'll get off my soap box now.

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Gunsmithing since 1961