Haven't we had this discussion once already? Maybe that was someone on another forum. First thing, loose primers in large quantities are extremely dangerous to handle, and are subject to sympathetic detonation. People have been killed handling large quantities of loose primers carelessly. Large rifle primers are .008" taller than large pistol primers. Small rifle and pistol primers are identical in size; rifle primers have thicker cups. My personal take on this situation would be to use all of the small primers for pistol ammo, assuming that your revolvers will ignite them consistently. That way you don't have to worry about piercing or blanking pistol primers in rifle ammunition due to excessive (for the primer cup thickness) pressure. Treat them as magnum small pistol primers. Sort the large primers, and treat them all as 'magnum' variety primers for their respective application (rifle or pistol), for the same reason - pressure.
A more cautious man might bury them in the back 40, or turn them over to the local Bomb Squad for disposal.