You're going to have to watch your overall length, and possibly might have problems with proper feed...
I'd recommend shooting some of the 4.2-grain loads, first, before going any hotter.
When you say "target", are you talking competition, or "just practice/plinking"? If the latter, 5.5 grains of 231 behind a 200-grain SWC is a pleasant load to shoot. 5.8 to 6.0 grains will just make IPSC major (old days IPSC).
FWIW, Art
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