In game use are currently using the M203's as grenade launchers for the US army side. But currently the 203 is be phased out of the US army and is being replaced by the M320. All infantry OSUT privates are being trained on the M320. The M320 is a handheld or rail attached grenade launcher with the same characteristics of the M203 on the moved the side to a side mounted side in stead of attaching it to the top rail system. https://en.wikipedia.org/wiki/M320_Grenade_Launcher_Module This is just an idea to keep game play weapons up to date.
Remember that the only 2 branches that are currently guaranteeing jobs to the enlisted are the Navy and the Army that I know of. Like gunbattle said do what you want to do, I had people pushing me to do this or that, but I choose Infantry and that is one thing that I'll never regret. Now yourself you want to see combat but not be a marine or join the army. That is tough because I know a few guys who joined the Air Force and now they are headmasters which is awesome, but they aren't where they were hoping to be.