I use 24.6 grains of Benchmark with the 60gr V-Max but I would not start there. Hodgdon has 24.6 as a Max load so you should probably start at 24.0 and work up since your new at reloading. Max COAL for your R-15 will depend on your magazines, but I get away with 2.260. I like the CCI BR-4 primers with the harder primer cups for use in the ARs. Don't go for the hottest load in the book for your AR since it's rarely the most accurate, and is harder on the gun and your cases.
Benchmark is the best powder Iv'e used in the AR-15 so far. It's not temp sensitive, meters better than Varget, and you don't have to deal with the compressed powder charges.
