I want to be able to hold on a zeroed [elevation] point of aim and have the bullet neither rise or fall from that point of aim more than 4 inches. The load propels a Saeco (O58 or 454) .452-inch 300-grain SWC-GC bullet @ 1600 fps.

I can achieve this, I think, using the "by guess and by gosh" method of moving my target until I find the maximum distance that my point of aim's elevation that drops less than 4 inches. I'm pretty sure there is a formula or set of tables that will make this job much easier and quicker, but I don't know what it is or where to find it.

Anyone who has a shortcut for finding this distance, please identify it for me.

Got to JBM Ballistics on the web. Pick a Hornady .452 300gr XTP for your bullet, and fill out the rest of the form with your other details. Change the range to 300 yards, and the increment to 25 yards. The BC on the Hornady bullet will be close enough to your bullet.

That will get you very close to your setup. Probably within 10 yards. Your load is probably going to have a point blank range of about 160 yards. It is close to my 454 load with a 300gr WFN cast. I am at 2.5" high at 100 yards, and 4" low at 150.

Jeremy

I've sighted all my handguns 2 1/2" high at 100 yds. for 30+ years.
Most "fast" single shots tend to be dead on about 250.
Most revolvers tend to be dead on about 150.
I get the true zero by hunting groundhogs with a range finder and memorizing the 0.
12,800 groundhogs give me excellent data for my 40+ handguns.
Things in the real world don't always agree with what computers tell you. Never seen a computer pull a trigger.