7.62 would require a different zero.
Here is one you can download and print.
http://home.comcast.net/~j_colt123/Red%20Dot%2025yd100.pdf
Some more options here for download.
http://www.ar15.com/forums/t_3_18/556355_Improved_25M_AR15A2___A3___A4_and_AR15_Carbine_Zero_Targets____Calibrated_for_50_200M__100M__300M.html
So it would seem just group 1.5" below point of aim. No zero crossing at that close of a zero. Investing in a laser bore sight is not a bad idea as well.
Brownell’s has a laser boresighter for $40. Takes all the work out of it. Plus you can check your sights at any time to make sure they are perfect. Works for high scope, low scope or open sights.
7.62?.........
Ever heard of Google or Bing?
Loose lips really do sink ships!
Stick a 3/4 inch sticky dot on a piece of paper and sight in at 1.25 in. low for a decent 100-200 yard zero. No reason to get fancy for a target at 25 yards. Best reason to own a 308 is for distance shooting. Well, that and punching holes in tougher stuff than a .22 will go through. You will still need to do some work out further distance, but that will make it easier to sight in out there.
Search for RIBSZ on ar-15.com
Just print them, this is one of several sights that have the downloadable .pdf files.
Try the 25m AQT targets from Fred’s (www.fredsm14stocks.com).
I use a paper plate a ruler and a crayon
TT
25 yard sight-in will shoot high every time because of the natural rise just after the bullet leaves the muzzle.