Has anyone else noted the difference between the older (grey-ish) ZAN 41 grain .25 caliber and the new (silver/shiny) slugs? The 41 grain (old) from a Superior Slug liner at 955 fps is lights out in my 700mm Impact. The new ones I couldn't group any better than a softball at 100 yards. I'd love to be able to get the old version, since the new version is useless to me...