I have to rely mostly in experience, as I have not delved deeply into science.
Your depth of rifling, barrel length, twist, patch, lube, and powder will all have an influence.
Depth of rifling, for instance, in a 1/48" twist barrel designed for bullets will prevent you from using large powder charges, or you start to "strip" out of the rifling. I found in my TC Hawken that about 80 grains was the maximum I could use for hunting, and that 50-60 was my best for target accuracy. Deeper rifling, thicker patches, shallow, thinner.
The depth of rifling will have an impact, so with deeper rifling you should be able to bump up the load a bit and pull off a bit longer shot. My hand-built Hawken has a longer barrel, deeper rifling, and appears to prefer a 120 gr load of 3F. Don't understand the science, but that's what it digests best for target shooting, for hunting I use a slightly larger ball (.495) and 140gr.
More details and such, but I find that about 125 yards is my limit. I am actually more accurate with iron sights than a scope, mostly because I have shot so little with a scope. I would not take a longer shot on deer than that.
For elk, I have a .62 rifle, with a 44" barrel. So all the variables are different yet again. But due to drop, etc, I would hold myself to 100 yards.
And the old saying of "beware the man with only one gun" at a shooting match. My .50 has been shot so many times that some days I feel like I can close my eyes and punch center, but I'm not as familiar with the 62 so I will be a bit more conservative.
I guess all this goes to say, is that you need to work through loads and patch/ball combinations and find what is going to work best for your rifle. And then shoot it a lot!