You can't experiment too much if you have an interest in accuracy. My favorite .44 Special bullet is a 200 grain flat nose plain base cast from a SAECO mould that I had opened up to cast .432" diameter. I've tried a variety of powders including Bullseye, Titegroup, 231, Unique, HS-6, and 800X. Best accuracy has been with Herco, a powder that doesn't enjoy great popularity these days. It's slightly slower than Unique. It seems that very few who have been handloading less than twenty years or so are familiar with it.