Get another .204 because it will do everything you require. The only issue with .204 is getting decent brass and the best is v expensive. Failing this a .222 would be my second choice. As for speed surely a 39 BK at 3,700 fps is quite quick enough, frugal powder use and no discernible recall and most important minimal noise. Point blank zero at 250 ish yds its just point and kill.