Agree with using a pack as a shooting rest. It is a great stabilizer, especially if you can lay it on a rock or log or even in sage brush. I find it to be just as stable as a bench.
Back to angle shooting. That was a real good article in Grand Slam and some good posts also. Let me see if I can muddy the water a little more.
The triangle diagrams in the Grand Slam article were good, I like pictures. Bullet drop is affected by gravity, and the quantitative affect is based on time. The longer the bullet flies, the farther it will drop. After 1 sec, the Earth's gravity will pull the bullet *down* about 16 ft. It will pull it down 16 ft toward the earth. So, if you are shooting up at a 45 degree angle or shooting level across a field, your bullet will still drop 16 ft after 1 sec of flight.
OK, back to pictures. You can diagram this by drawing an arrow from your hypotenuse (your bullet/sight line) in the direction of gravity (straight down). The bottom/tip of the arrow represents 16 ft after one sec. Then draw another line (we'll call it the drop line) from the barrel in line with the bottom of the arrow toward the target. The steeper your angle gets, the closer your drop line gets to your sight line, until if you are shooting straight up the arrow, the sight line and the drop line are all the same.
When you shoot straight up, gravity still affects the bullet exactley the same as if shooting level. It still pulls the bullet 16 ft toward the Earth after 1 sec. But the bullet's path toward the target is not affected since the path is in line with the target and gravity.
A good way to demonstrate this visually would be to get a string and tie to something close to the ground. Then get a straight object like maybe a stick and tie it to the string about 5 ft from where it is tied off. Pull the string tight and lift it to different hieghts and observe how the stick gets closer to the string the higher you lift it.
OK, that is the basic concept, but it doesn't totally apply to shooting, as pointed out in the Grand Slam article. It is complicated by the fact that our sight line and bore line are different. Therefore it requires someother calculations to compensate for that when related to actual shooting.
I hoped that helped.
Mark
