As for SK ammo, Rifle Match, Standard Plus and Magazine ammo are all made on the same machines to same standards and same components. They do lot checks and lots that shoot the best are sold as Rifle Match, worst are Magazine. RM and STD+ are often indistinguishable in accuracy, they come from assembly lines 1 and 2 only, Magazine normally come from lines 3 and 4. Lot number on the box includes date of production and line it came from, you just need to decipher it.