Shawn over at LooseRounds sent me this awesome chart a month or two ago:
The chart has dope on three AR15 platforms. You can see that the A2 rear sight elevation is easy to memorize, but also very course in its adjustments. The Carry handle of an M16A4 and M4 carbine is a 1/2 minute adjustment but the shorter sight radius of the M4 makes it a little harder to memorize the rear drum changes… but not too much. It also shows that an AR15 with a 20 inch barrel and a detachable carry handle has very precise adjustments. Committing some of this data to memory (or taping it to your butt-stock) will only improve your shooting so I thought I would share.
Remember that last year Shawn took a box stock A2 rifle and then he took an M4 carbine out to 1000 yards. It’s an understanding of data like this that will allow you to be the guy at the range who has the knowledge to make calculated adjustments to your weapon instead of a point of impact guessing game.