If you go to a mil dot reticule it will work for any caliber. As for a range finder like Shepherd www.Shepherd scopes.com. with the mil dot it tells you the range to target and then you use come ups for your particular rifle
Not really sure if there is a universal specific 5.56 or 7.62 recticle. Magnification could play a big role here. Springfield does make scopes specifically for 5.56 and 7.62 with their proprietary recticle.
