Join Date: Sep 2010
Location: Upstate NY/Prescott AZ
Let's look at a couple of examples, per one of my favorite ballistics programs that works really well for me.
a Federal American Eagle 223 55gr FMJ factory load, zeroed at 200, has it's initial POA/POI at 44 yards...granted, not much difference at the 50 yard mark (.2 inches).
Next, let's look at 308WIN, same manufacturer, 150 grain FMJ. Again, we'll zero at 200.
Initial POA/POI is at 36 yards, but now, the difference is .5 inches at the 50.
Next, let's look at a Federal Power-Shok 22-250 55 grain PSP...again, zeroed at 200.
Initial POA/POI is 55 yards, giving a 50 yard difference of .1 inches low.
If you're shooting matches, it's a huge difference.
For hunting purposes, the 50/200 rule works, as the differences are nominal (easily minute of deer, elk, coyote, rabbit, etc.), as the variances are very small for the application. It's not like a difference of minute of trash can lid.
So, depending on your application, and your desired precision, yes, it can work.
As for cross winds, it's totally dependent on wind direction, angle, bullet spin, and distance.
As the bullet travels from the muzzle to the target, it slows progressively.
Meaning that, the further it has to travel, the more cumulative the effects of wind and gravity.
At 200, depending on caliber, velocity, and projectile weight, the effects will be lesser or greater, based on your selection of cartridge.
Admittedly, at 200, there will be small variances, less than at 500, but more than at 100. How much? Depends on a variety of factors, and without knowing your application, I can't give you an idea as to what those are.
I know that a 15 mph cross wind at 90* to my shot, using my 300WSM gives me a variance of about 8 inches at 300 yards. That's using a 165 grain Nosler BT Fed Vital Shok ammo, 1/10 twist Savage 16 bolt gun.
Alternatively, in my 308WIN Rem 700, using the 170 grain PSP, same wind, same conditions, I have a difference of 24 inches.
What's the main differences between the two rounds? About 400 FPS velocity difference and the bullet ballistic coefficients are dramatically different, the PSP being about half as efficient at the BT.
My suggestion to you is this - figure out what round you're looking for that information for, then find a decent ballistics calculator program that allows you to input your specific information for your chosen cartridge. Most will.
Then, using the tables for basic reference, test out the tables vs. real life conditions, and see what your rifle/ammo combination does.
Then build your specific table that's tuned to your rifle/ammo, and tape it to your stock for reference.
"If you carry a gun, people will call you paranoid. That's ridiculous. If I have a gun, what in the hell do I have to be paranoid for?"