If all elese fails try a Sierra match bullet in the appropriate weght for your twist. Use lighter bullets if you have to. The .223 is generally less finicky than the 22-250. Try different primers. Read the RCBS load manual, don t be afraid of magnum primers.
Ball powders get a magnum primer in the large cases.
Have not seen a need in .223. Buy at least 500 at a time. Don t buy an 8 lbs. If I had one company to choose for everything, it would probably be Winchester. Everything I have ever gotten from Midway was prompt and of excellent quality.