I've got a lot of imr4064 powder laying around, and use it in my 300wsm and love it. I just got a 338 Lapua magnum and want to reload it as well. I've read articles on people using it on 300 smk bullets out of a 375 H&H, with decent results, so I figured why couldn't I use it out of my 338 lapua. My question is what grain of powder should I be using? And how much is too much? I will be using lapua brass with imr4064, federal 215 primers with 300 smk bullets. I plan on using the gun for 300-1000 yard hunting and shooting with friends around the house. Thanks.