The Carbine is better in the hands of marines due to it's rof. Just 14 carbine marines can destroy the toughest Brutes. Also, it's useful against perched Jackal snipers. The BR's individual bullets don't have much stopping power and it's spread makes it outmatched against snipers. The Carbine has some degree of stopping power and is a bit more reliable. The encounter I'm speaking of is immediately after Sierra 117 rally point alpha, where there are 2 inaccessible Jackal snipers on the other side. Knocking them into the water renders them unable to fire at you. Much better than trying to get a headshot on them with the BR. But what makes it really great in campaign is that Arby carries it. You can easily replenish and go through an entire mission with it (I'm thinking of levels like The Covenant). just like the good old times (CE missions). [Edited on 08.23.2012 8:27 AM PDT]