Its not finicky for powder and data used can be from the 223, 5.56 NATO and 223 AI (be careful with any AI data) and worked up.
I like using slower fuel and hitting a velocity benchmark.
My favorite powder for 50-55's is Benchmark and 27 grs. will get 3,450 from most 24" tubes with the 50gr. bullet WITH Herter's cases (they are heavier than R-P's of every vintage).
R-P cases usually will take 1/2gr more to get the same speeds.
Generally, its capable of 223AI or 5.56 velocities without issue.
