You might want to consider using Rem 6 1/2 or small pistol primers for this cartridge. Pressures are low enough, and the weaker primer will not push the bullet out of the case before the powder charge is fully ignited. This is one of the causes of erratic accuracy of this round. Also, make sure your expander ball in your sizer die is .223 dia, which is the proper size for .224 bullets, as the newer hornets are made. Some dies may still come with a .222 expander ball intended for the old .223 hornet bullets. With the old .222 expander ball used on .224 bullets, you will occasionally get bulged case necks, as the hornet necks are of very thin brass, bulging usually on just one side, and the bullets won't always seat straight. I had the .222 expander ball and contacted RCBS, and they sent me the proper size replacement for free. Hodgdon Lil Gun is a good powder to try for the hornet.