I am new to AR type rifles but not reloading .I have a 223 varmint bolt gun that's about 25 years old . I have reloaded for it in years as my interest in guns went to Black powder cartridge and WW2 military rifles . Now that I have anAR-15 I started reloading for it and found among my primers a box of federal small rifle primers # 200 which I see now are designated as pistol primers . As you can see by the picture of the box .It says there for rifle and high power pistol .