I agree with most of the above, but especially with CVA54.
Your upper body will always point a weapon to the same place, whether a hand gun or a rifle, etc. They will be different between the types, but always consistant.
The body can be trained to compliment the above, but takes practice. Here's how I learned it.
***** Safety first! This DOES NOT require a loaded weapon. *****
1. Look at your target (doesn't matter if its high, low, or in front of you).
2. Close your eyes.
3. Bring your weapon up to point where you think the target is, allowing your body to move naturally.
4. Open your eyes.
5. Is the weapon on target?
6. If not, move your body until it is, without forcing it (make it comfortable), while looking through the sights. Continue to look at the target for several seconds. Don't study the target, and let your body stay relaxed. Do not fight the gun, or your body, into pointing where "you" want it. .....RELAX ............... It will point itself.
7. Lower your gun.
8. Turn slightly so your body must move, or stand square to the target (when there is a question of safety).
9. Again, look at your target.
10. Close your eyes.
11. Bring your weapon up quickly (>1 second), DO NOT think about it (make it to fast for that).
12. Open your eyes.
13. If it's on target, that is your "natural point of aim" that you have adjusted for use with that weapon, and your body will learn this. (Practice until you can do this without thinking)
14. If not repeat #6 above.
***** Safety first! This DOES NOT require a loaded weapon *****
With practice, you will find that your body will automatically point correctly.(muscle memory) And after more practice, your will find that it will apply in any position because your body will adjust, from memory, to get your upper body aligned to point "on target". It will work whether on flat ground, uphill, downhill, or even with bows out of trees. And after even more practice, you will find that you'll only have to do the above steps once or twice when you change weapons.
This is what a good snap/offhand shooter does (uses his NPA) even though he may not know what it is called.
And, thanks for the question. I have never actually thought this through. I know I do this, but I hadn't ever had to explain. Not even while on active duty as a range NCO for the US Army.
Hope this helps someone.