I've done ALOT of chronographing with the same load charges, bullets, brass, COAL, ect. and have found the BR2 yields lower (in most cases, not all) extreme spreads with stick and ball powders in a .308. This is compared to the 210m. Your also going to see anywhere from a 15 to 25 fps increase in velocity using the 210m compared to a br2. Now this isn't empirical evidence or anything just my experience. For my loads I know I'll be shooting while hunting in cold weather I stick to the 210m because the ignition seems to be a little better with ball powders. (2000 mr). But for specific long range target shooting where ES is a very important factor I test them both not only for accuracy, but more specifically which is going to give me single digits Es.
Just my thoughts. AS