Sounds like a good idea. Ever since Resistance introduced the handguns and shotguns, I've wondered how to make them work in a campaign. The trouble is (just like the Resistance campaign) in the first mission you pick up a shotgun, kill a Russian, and grab his AK-74. After that, you never go back. There's no reason to.
Perhaps you could use some excuses, like this mission will be in town, and you can't exactly hide a RPG in you coat pocket, so it's handguns only. Then you'd have to do the scripting to let the player carry a pistol and walk past the guards so long as it's not in his hand. There's a thread on that in scripting at the moment.
Or, ignore the ability to carry over equipment from mission to mission. Just because it's there doesn't mean you have to use it. Make the briefing say something like "you've run out of ammo for the AK's, and are reduced to using shotguns. Go kill some Russians and steal their guns". Or perhaps hand out some Uzi's or other random stuff.
I'm assuming the Soviets are the opressors here. That is hardly necessary. Resistance against US forces could happen just as well. At the risk of being flamed, I guess that would be Grenada.