Me and my brother have been playing co-op split screen and we started at the same time and right now I am still a corporal and he is already Sargent grade 1 and all we have been doing is campaign
And the only thing different is I have Xbox live
You get less cr if u play on co-op
Matchmaking is key. Try SWAT for quick games and decent credit payouts
If you’re gonna rank up solely off of campaign, you’re gonna be there for a loooong time. Trust me. I only got to General off of Campaign and Firefight and some Forge sessions since I didn’t have LIVE until Halo 4, and it took me about two years. Might’ve been less, might’ve been more. Point is, you’re gonna want to jump into some MM to at least boost it up. Get those challenges done, pop headshots in SWAT, whatever. I’m sure there are some videos on YouTube on how to best increase the amount of credits you get. Just be careful if you find videos that promote modding and stuff like that. Do it legit.
Grind Matchmaking
OP play firefight online co-op with your brother, it will be a lot more fun to play and you will rank up faster too then campaign.
Are you sure that your brother hasn’t played in matchmaking. And do you have Xbox One or 360 because on One all profiles on your Xbox can play online.