WC872 is a military surplus gun powder originally used for the 20 mm Vulcan. (Cannon powder.) It has a burn rate a little slower than H870. It is temperature sensitive. I have read that it is not good in warm weather and will produce occasional flyers. (DC)
I got mine for $32 for 8 pounds plus shipping, etc.
I really liked it because it produced very good velocity with little to no pressure. The 28 inch barrel probably helped. I was getting a hair less than 3500 fps with 7 mm RUM - 160 grain Nosler Accubonds and could have gone higher. For various reasons I was not shooting too well during this load development and went back to Retumbo.
I am interested to know about H50BMG. It has a burn rate in the same range as WC872 and is a Hodgdon Extreme powder which is supposed to be pretty temperature stable.
I would say Darryl Cassel would be the resident expert to ask about this powder. He has commented on some of my WC872 questions and was very helpful to me.
If you go back to the home page and do a search on WC872 you will find several threads conatining WC872.
Doug