If I zero my Ruger SRH .480/7.5" barrel @ 25 yards loaded with Hornady 325 gr. HP/XTP's , where do you think it'll hit at 50 and 100 yards?

If I knew the velocity I'd plug it into my Quick Target program but really the only way to know where it's actually going to hit is to shoot it at those distances.

I'd zero at 50 or 75, 25 is too close to zero for shooting at extended ranges.

Short range zeros introduce too much error. Test it at least as far as you're going to actually shoot it. Given past experience, I'd probably first sight it at 100, check it at 50, and, depending on trajectory, probably adjust it so it's the same amount high at 50 as it is low at 100. Unless you're trying to shoot squirrel heads, that'll be good enough .. certainly good enough for boiler room shots on medium game animals.

Tom

Seconded. I Zero all my big revolvers for about 75 yards and I haven't been sorry yet.