Please dont 'mis' understand the statement about Unique and assume its a low pressure load powder, it is not and once you reach and think you can exceed the top end load data it can over pressure the firing platform. It is often used for reduced velocity loads and I use, and like it a lot; but remember, a little goes a long way. In my 44 Spl and light loaded Mag days (hey, a 44 aint far from a 45 or a 240gr bullet from a 250)I used 6.5-7.0 gr Unique a lot for fun shooting, and 7.5 was a good all rounder (for Skeeter and me), 8.0 will have plenty of beans for about any work with an open sight handgun and 9.0 (IIRC) about duplicates the old 45 black powder load ballistically.. Put any of these in a short carbine and you should be able to get 150-200fps more velo than the load in a handgun.
As for 200yd., and all, my friend Mick has a Rossi 92 in 38Spl. that hits the 150-200yd. gongs (not real big either) repeatedly with 158 cast PB over a full charge of black powder. Your 45 carbine should do as well.