Water dropping is akin to heat treating, though not as consistent. Hunting bullets for revolvers/carbines should be relatively soft..............air cooled. IME, air cooled BHN changes/gains over a three week period, will only be 1-2 BHN.............depending on alloy
antimony composition. Not enough to worry about, and softer would be better, anyways. I'd be more concerned on how they shoot\group.
Need higher BHN, for rifles, oven heat treat. They'll be about as hard as their going to get, after water quenching.
Now, I'm referring to conventionally lubed bullets. Powder coating is an entirely different animal.