Halo 4 map pack achievements..

Will they be map pack only (like in Reach), or can I get them on other maps too?

it does not state a map requirement but it probably has maps that would make such achievements more possible to obtain

they don’t seem to be map specific thank god. what I want to know if you can get them in custom?

Doesn’t look like they’re Crimson specific. I bet they would’ve told us if it were.
Still: they’re challenging. Me like!