Winchester spherical powders are known for their
consistent burn rates and clean burning characteristics
and are widely used for reloading shotshell,
handgun, and rifle ammunition. A magnum rifle powder found in many Winchester factory loads
like 300 Win. Mag and 270 Winchester. Often gives the highest
velocities in the belted magnums. Flows extremely smoothly
through most powder measures.
Sinclair, Issue:3B, Page:101