What will you be shooting with it? What is the barrel twist?
If the barrel twist is slower than 1 turn in 9" and you want a fast accurate varmint killing bullet you can use the 45 and 50 grain varmint bullets or the 52 or 53 grain match bullets. If the twist is 1 turn in 9" or faster there are some lightweight varmint bullets you shouldn't use as they cannot stand up to the rpm imparted by the faster barrel twists. The 1 turn in 9" Mini14 would blow up one or two out of ten of my old 45 grain varmint loads meant for the 1 turn in 12" barreled M700 VS.
The best groups my rifles ever shot was with IMR4198. But you need to weigh every powder charge (stick powder) to get consistent powder charges. Not a big issue for a few rounds a day shooting ground hogs or crows.
All by latter year loading still shows IMR4198 to be good with up to 55 grain bullets, but in the name of efficiency I've started using BLC2 for the 55 grain loads fired in the AR15s. Not as good as IMR4198, but better than the other powders I've tried. I've never loaded anything heavier than 55 grains for .223. Some day maybe. Got 69 and 77 grain match bullets on the shelf, just can't seem to get around working on some loads for the 1 turn in 7 and 8" ARs.
