Try that method; I don't think you will like it. Using the pic in your post, you see that you have a distinct aiming point at 325 yards (bottom dot), and then the next one, the top of the lower vertical post, is only 55 yards further away. A target at, say, 355 is somewhere in that no-man's-land of unmarked vertical line in between the two. You have to estimate where on the line that unmarked sweet spot is, and then hold it on target, which in the case of an animal is another unmarked spot on the side of the critter.
I've shot a bunch of coyotes with .45-70's; a couple of H&R Buff Classics, a C.Sharps, various Pedersolis, etc. out to distances of slightly over 325 yards. Almost all of those guns were equipped with decent-to-excellent quality Vernier rear sights that would allow me to dial in perfectly at known distances...like your scope does, once you confirm the actual (not published) drop figure for each dot on the reticle. For target shooting, even at much greater ranges, they were great; for animals at lasered field distances, it is much easier to simply use the drop of your particular load (learned through trial and error), and then quickly guesstimate how many coyotes or "fractional coyotes" you need to hold over to make a hit (a coyote is about 24 inches tall). This way you are still shooting at an unmarked spot on or above the critter (like we do with all hunting shots) but you are at least aiming at it with a solid, distinct point; i.e. the front sight or the center crosshair. Reading over this, it sounds complicated...but it is simple to do with some practice. Eventually, it even starts to work!
Of course, there's still the wind to worry about...
So, once again, it all comes back to the .300 being more versatile...but the big /45-cal boomer is just so much fun!
