Re: 308 Vargert or Rl-15
I think they're almost the same exact thing. I think variables such as environment, rifle, barrel, components make more of a difference than the difference between these two powders.
Half the people say one is cleaner than the other, half say one is faster than the other.
As far as clean/dirty, I can't say. They're both pretty clean. As for temp insensitivity, R-15 seems pretty good, but Varget has been very insensitive and that is because I've used it more and can confirm this. Not enough use with R-15 for me to say, but it shows that it is so far. R-15 has given me a little bit more FPS than Varget with comparable charges, but again, until a few hundred (yes HUNDRED) rounds go through the chrono in various conditions...can't say.
Alliant says R-15 is the powder used in M118LR.
My conclusion is that they're both excellent powders. Both have been highly accurate for me. The charges are the same. Velocity about the same, so close it doesn't matter. Both temp insensitive. Both relatively clean compared to older powders.
While this might be not the best mentality for reloading, after testing these with chrono etc, I consider them interchangeable for MY loads and practices. I don't load max or super-hot.
They're both accurate. Just under 1/2moa for me.