How far can I shoot?

Whether it's a pneumatic. 177 pellet gun or an Abrams tank. If you can't hit it at 100ft. You've passed your limit.

I'd say a moose heart is roughly the size of a basic paper plate. I'd set up a plate down the range and shoot it. I place another further until I can no longer place groups on the plate. I've passed my limit.

I use a desert plate. when you can no longer put the first cold barrel shot from field positions on it you've found your limit. In hunting only the first shot really matters.