Match ammo is made with the machines running slower (helps reduce the impact of the slop in the tooling tolerances), and is also generally made when the tooling is new. As the tooling wears, it gets relegated to "standard ammunition" and machines are also sped up (since standard ammo has more generous QC requirements). Hence why some lots of standard ammo are just as consistent as the match stuff; either the tooling is still in good shape and/or the speeding up of the loading machinery hasn't impacted quality...yet.
At least that has been my experience, though admittedly, most of my experience in ammunition manufacturing has been with rimfire cartridges.