The federal black pack that have been on sale at really good prices recently,look and perform almost exactly like the minimags.The bullet has a pretty identical appearance to the minimags..I recently shot groups at a 100yds with both the minimags and these bulk black packs and the grouping and point of impact were identical.No reliability issues either in my GSG 16(which can be pretty fussy with bulk winchester and remington ammo)
I've heard the Federal black pack are CCI Mini mags as well. I read a comparison post where they had the bullets next to each other and they look nearly identical. Performance was same as well I'm told.
Cabela's has the 1100 round black pack on for $65 right now, regular $99.