OAL should always be determined by the individual loader by performing a plunk test on the gun(s) that's going to shoot the round.
If anyone follows my posts (doubtful
), they know by now that I am without a doubt, a fast powder centric loader. I clearly tend to use faster powders than most for a given application. That said, I would not load a 147g with Red Dot or HP-38 - they're both too fast for the weight and are bound to pressure spike, unless you're really careful. I would strongly discourage it.
My 147g lead recipe is 5.0g HS-6 - a medium-speed powder. (It's a FP, not a RN) It's a good recipe. Burns clean and consistent. 890 fps through a 3.7" bbl; and 971 thorough a 5" bbl.
HS-6, Unique, or AA5 (and others) would be good choices for that bullet weight.