Excuse me josebd, but do you own a reloading manual? In the back of one are usually a conversion and or comparison charts. These would tell you what numbers are small pistol/rifle and large pistol/rifle primers, If you do not own a reloading manual, go out and buy one or two and if you do own a reloading manual look at it and read it from cover to cover.
Yes you can always replace a mag primer with a standard primer and visa versa. But if you are going to replace a standard primer with a mag primer youll need to down load your load by 3% to 5% depending on the case size and work back up. In either case you need to ask yourself or others is this replacement of primers going to work for you or not. Most of the time it is trial and err. There is not enough data to know for sure. There is the geometry of the powder, material used, and the percentage to which those materials are used, the geometry of the case and case capacity, and then there is the bullet setting depth and load density, but you cannot forget the bullet itself, the weight and construction (for resistance). You just cannot or highly should not replace a rifle primer with a pistol primer but you can replace a pistol primer with a rifle primer, just be a were that a large rifle primer is taller then a large pistol primer. But if youre not really sure what youre doing than do the standard.
Donna
