Okay guys. I've been pondering this for awhile. At what length of barrel and twist rate do you decide on a fast or slow burning powder? I've read that you want a slow burning powder in a longer barrel rifle so you can maintain higher pressure longer till the bullet leaves the barrel. Faster powder for pistols and shorter barrels. So what's the deciding factor on length? I'm shooting a 20" bull barrel in my 700. Would a 20 need a faster burning or middle of the road? someone recomended h380 but he mentioned its a faster birmig middle of the road?