Putting aside technology in the form of laser rangefinders and rangefinding reticles, there are several methods available to the shooter for range estimation.
About David Watson
Author David Watson learned about rifles from his father, as a youth in Australia. Following a long shooting career as first an infantryman and then an officer in the Royal Australian Army, Watson turned to gunsmithing, specializing in accurizing vintage and military rifles. The ABCs of Rifle Shooting is his first book with Gun Digest.