Unless we are talking fallout, I"m sheltering in place.
You can't just have more than one!
1) AR
2) SKS
3) 308 Hunting Rifle
4) AR
Yeah, this.
If you need to go mobile and blend in with a group, then you're stuck with a highly concealed pistol. 9mm would be my first choice, but a pocket gun like the Ruger LCP is more likely.
A lever action rifle, like a Winchester 30-30 would be less "scary" in a group than an AR and allow you to hunt anything up to a small bear. Although, I'd probably still go with my Colt M4.
The other advantage of a pistol is being able to hide it quick. This would allow you to perhaps go through a group checkpoint and come back later for retrieval.