I've never understood how anyone uses range balls to determine their yardages anyway. Range balls are usually so much different from the balls that most players use on the course that it has never made any sense to me. Even going from one range to another can produce different results. Unless you are wealthy enough to be a member at a high end club where they have real balls on the range, I just don't see how you can make that valuation. I get my yardages by playing on the golf course. I measure where I am from the hole with my rangefinder, then I select the club that is about right for that distance, hit it and if it's a good hit, I can tell by where the ball ends up how far I hit it. I adjust the rest of my irons accordingly up and down the line, and verify with each successive approach shot. It shouldn't take long at all to have a very good idea how far you hit each club. Long before the days of lasers and GPS I still established it the same way, except that I used course markings - 150 yard markers initially, then sprinklers when that became common. Not as precise, but then like 99% of amateurs, my game doesn't require it.