After doing a good deal of searching, the only thing I figured out is there seems to be some contraversey over the exact recipe for this load. Because I'm cheap, and my LR-308 can do 1/2 MOA with this load, I put a lot of time into figuring it out. I believe I have done it. First,like many others have done, I pulled and measured the charges for an entire box of 20. The avg. was 42.5, a few were 42.3, none exceded 42.6. Based on this and the advertised velocity, a look at the Sierra data will indicate IMR 4064. Next, I pooled the powder and measured the length and circumference of 50 random kernals. I also weighed 10 samples of 100 kernals then reloaded with that powder making each charge 42.5 grs. The length of the kernals always fell between .080 and .083, the circumference was a constant .033, and every sample of 100 kernals weighed 2.6 grs. With this data, I went to the local reloading supply shop (owned by a friend) and set up in the back and started measuring samples. IMR 4064 was indeed a match. I loaded 20 rounds with 4064,fed match primer, fed brass, and chrono'd, the velocity and POI were an exact match. I do hope I've helped someone or maybe answered an often discussed question. I was going to wait for a rainy day to do this but, I just had to know. The average velocity for my REPR is 2050 fps, 80 deg F, 4900' DA with this load. I hope it will modify with the same results in better brass.
