need advice on long range setup

[Greyfox]

so you gies dont think that information was true that for every 20 degrees farenheit change it moves your bullet a whole MOA up or down? I was just curious because it was a marine sniper that told my friend that and i was curous if you gies had heard .

The elevation correction is largely dependent on the distance to the target and caliber. For example, with my 6.5x284 I don't pay too much attention to temperature changes under 20F for distances below 600 yards. At a 20F change an 700-900 yards, 1 click(.333moa) up. At 1000 yards, 2clicks(.666moa). If the sniper was talking about a 308 with Federal 168 Match, the 20F change is in fact a 1moa change in elevation at 1000 yards. That's temperature only. Humidity and pressure changes depending on extent could require further consideration. Hope this helps.

 

[IdahoCTD]

The angle compensation can be done by you in the field if you use a calculator or a shooting program. You will need a cosine/angle indicator that mounts to your rifle. It does make a difference in the angle. If you find yourself shooting a steep angle, it actually shortens the distance the bullet needs to fly. For instance, a 220yd target I shoot at, has a .98 cosine. It shortens the distance to 215yds. Its only a drop of 5yds, but at longer distance, it can make a real difference.

Temperature will effect your drops. No some of that has to do with powder burn rate speeds at different temps. The other part has to do with air density.

Tank

The distance didn't change. A rangefinder reads line of sight distance. The angle changes the effect that gravity has on a bullet. The steeper the angle the less it effects the bullet. Since gravity has less effect you dial for less distance. The distance didn't actual get shorter it just appears that way to the bullet and your ballistic program/drop chart.