I understand your frustration. Primers along with other some other reloading components are getting very difficult to purchase. Especially 223 and 308 components. The new Prez scare has got people hoarding large quantities of these components. I have not checked in the last couple of weeks, but cases for those rounds are also difficult to get; the last I knew. Personally, I bought a large quantity (for me) of primers last fall. They were getting hard to get then. I could not find any locally and had to order on line and swallow the Haz-Mat fee. It was blamed on the war effort at that time.
Not only are the primers different in primer mix; t is my understanding that small pistol primers have thinner cups than small rifle primers. In general pistol cases do not see as much pressure as rifle cases do. In some of the newer - high pressure pistol cases like the 357 Maximum; small rifle primers are recommended because of the higher than normal pressures for a pistol case are used. I would think that you would surely get ruptured primers if you approach any thing close to working 223 pressures. If you cut back the powder loads to reduce pressures you might get by with the small pistol primers. If that is what you decide to do, be careful about what powders you are using. Some powders can be cut back to lower pressures OK, but others should not be used below recommended (listed) levels. Good Luck and Good Shooting
