"At what range do most actually test their reloads, different factory loads, etc.? Is 50 yards good, 100...?"
The only guns i reload for that are iron sighted are mil surp guns, they are just play toys that sit in the safe, i have those sighted for 50 yrds. I test my mid-range guns to 100 yards, i test long-range out to 200yrds. Pistol rounds, 15 yrds or less