If your intention is to just run one gun for CQB and outdoors then like has already been mentioned, they'll have to be compromises for either setting.
You may not want a full sized M4 for CQB as you'll just get in your own way when taking corners or clearing rooms. Something the size on an ARP9 might suit. A few lads use them at our woodland site and seem to fair ok!
I'd recommend getting a chrono at home so you can figure out what weights you can safely use while still being within site limits.
One thing that is often over looked when matching BB weight to optimal range is playing style! If you like to push, the extra bit of range you MIGHT get from a heavier BB may be lost / pointless if you like to run around like a bull in a china shop!
I stick 0.32's in everything I use outdoors that's not a sniper....ok apart from my click clack KC02 which I've got at 1J, this sends 0.4's close to 80 actual metres, or 200 Airsoft metres if you use that scale.
Indoors I run 0.25's but I'm fortunate enough to have separate CQB pistols and shotguns. So the hop dosn't need to be adjusted to suit where I play.
All the best xx