With few exceptions, the slightly faster than Magnum spherical (ball type) powders will give lower flash than flake powders. IMO, 700-X and Bullseye burn too fast to make them effective .357 Magnum powders. You've already found that you don't like 2400. Power Pistol and Blue Dot will turn your LCR into a flamethrower when fired at night. 3N37 and N350 are both suitable, but their more expensive then necessary. One of the best ball powders you can use for short barrel defense loads is AA#7. I am working with True Blue for my 2 3/4" barreled Speed-Six for much the same reason. What I'm trying to achieve is performance equal to or better than 9mm +P loads from an auto. That can be done with Ramshot's start charges for True Blue and their ballistician recommended it to me because it's not as position sensitive as some other powders. Their ballistician is actually employed by Western Powder Co. who owns Ramshot and Accurate so he can be consulted on either powder. A Lyman 49th or the P&R III manual would be helpful also. True Blue has outstanding pressure stability. Even though it is a medium burn rate powder, Lyman used it to the highest pressure level of all loads with 110 and 125 gr. JHPs and it will flash a whole lot less than the powders you're considering. I would recommend that you look at the data for either AA#7 or True Blue at their respective websites. The Lyman Start Charges for True Blue are actually lower than Ramshot's. So, with True Blue and Ramshot's recommendation for Start Charges, performance should be pretty good in the LCR.
