Are 250 to 300-yard shots feasible with ... the .444 Marlin or a (handloaded) 45-70, from that gun?
They can handle it if you can.
In my long-ago prime, I've hit clods of dirt about the size of a man's head at over 300 yards with some regularity using handguns with iron sights. I've seen the late Bob Milek out-shoot capable riflemen with his Contenders, and I've seen my friend Russ in South Dakota make life downright risky for prairie dogs at 1,500 yards from one of his Contenders.
