Well, shoot. Read the thread, the posters all make good comments, and we could go on forever as to which is the best caliber, bullet weight, etc. So, as a GHOF (grey haired old fart) of 75 and a hunter, shooter, LEO, and gunsmith off and on for nearly 60 years let me chime in.
I'm no ballistics scientist either but I have had a lot of general training and an old Army explanation of bullet drop was---mount a rifle parallel to flat ground, fire the rifle and drop a bullet at the same instant and they'll both hit the ground at the same time. In other words, gravity pulls on both equally and they both started from the same height. A 160 grain 30-06 or .308 bullet drops about 70 to 80 feet at 1000 yards, that's a lot of drop. They drop about eight feet at 500 yards although the 06 has a slight edge because of a larger powder charge and 200 fps or so more velocity. The faster the bullet, the farther it can travel as gravity is acting on it.
Another Army lesson was in shooting up OR down hill and it was pounded into our heads to shoot low. It your target is some distance away and either up or down hill from you, it may be say 300 yards away if you stretched a string between you and the target. That's 300 yards over the sloping earth. However, if you draw an imaginary line straight down from the uphill target or a line up from the downhill target, then measure your distance to that imaginary line it will be much shorter and that's the real distance wherein gravity will work on the bullet. Since it's a shorter distance gravity wise you'll overshoot if you use the actual distance of the slope.
My favorite elk gun in heavy timber where long shots are rare is a S&W 41 mag revolver. I've shot elk and deer with that handgun for years and also carry it on duty with my local sheriff's dept as my standard sidearm. My loads push a 220 grain semi jacket softpoint at just over 1700 fps. That's slow by rifle standards but still a lot of energy with the half ounce bullet (437 grains to the ounce). I also hunt with either of a pair of 45-70 revolvers with 10 inch barrels. These fling a 405 grain bullet at close to 1800 fps and they'll drop a deer, elk, or boar right now. I don't hunt bear but have fired in the ground in front of a couple of blackies with one of the heavy handguns to spray rocks and dirt in their faces. They ran one direction and I speedingly walked away in the other direction. I have no doubt either caliber would bring one down quick.
For rifles, I don't think a good 30-06, the uncle of the .308, can be beat. Bullet weights range from 90 to 220 grains. And an 06 is even a good squirrel gun, as is any thirty caliber, if you dump about two grains of Bullseye pistol powder in a primed case, and seat one OO buckshot (also 30 cal) in the case mouth with a bit of kleenex or toilet paper as a patch. This is deadly accurate out to 20or 30 yards, makes little noise, and has about zero recoil. Saves having to pack a 22 or other small gun for little critters for camp meat. When I hunt for big stuff with a 30 cal (06, 308, 30-30, even a 300 mag, I always take 15 or 20 of the appropriate caliber Bullseye/Buckshot rounds with me.
I also own and regularly shoot a 7 mag, a couple of 308s, two old 30-30s, a 45-70 single shot, and so on. I like 'em all. Mainly I'm a handgun nut but I do know their limits and long range is one of them. There's nothing better than a potent handgun nice and dry under your jacket in a chest holster when you've scrambling through snowy brush and rocks way up there, I don't like any rifle then when I need both hands to push and pull on low limbs and climb over rocks.
Anyway, an enjoyable thread and thanks to the initiator and other posters. BTW, to my experience, an 06 or 308 with a 150 grain bullet sighted dead on at 100 yards will be about five or six inches high at 200, back in the bullseye at 300, about 2.5 to 3 feet low at 400 and 7 to 8 feet low at 500. The bullet really slows down as it gets out there beyond 300 or so which is why the BC becomes crucial, the 'streamlining' helps retain velocity.
not gravity ? 
