Do a search. There's a useful discussion on Ask the Gunwriters where John Barsness talks about his article in the current, on newsstands now, Hodgdon magazine style data manual.
I have not tried it. My impression is that by design it meters well, gives a good loading density and is more consistent over temperature swings. For my sins I bought kegs of some traditional powders when I would have bought pounds pre shortage so I have lots of older powders to use up - I may die before I need the new powders.
On the other hand I do believe that say IMR 4064 which was one of the very early IMR powders does as well in some loads in typical weather as anything newer. I do believe the long log style grains of 4064 that don't meter well do take up space to pack consistently and so give consistent results at standard weather in traditional cartridges with midrange capacity and midrange bullet rates to give midrange expansion ratios. So nothing in the three new powders that demands a change but as Mr. Barsness said I too expect to use the newer powders for what they do have to offer. Arguably if performing no better than 4064 in some cartridges the new powders will perform as well in more cartridges.
Last edited by ClarkEMyers; 12/21/14.
