Federal No. 200 primers which were labeled "Small Rifle Primers and High Velocity Pistol". These primers should never be used in a high pressure round like the 223 Remington. They may blow out on the edge, cutting pock marks into the bolt face. Pierced primers may happen because of thin cups. In 1959, early 60's, Federal sold these primers. Now the 200 is for magnum pistol ONLY. If you must use in the 223, maximum pressure should be no higher than 40,000 PSI.