Oddly, the best way I've found to transport a long gun is in a golf bag. Add a cover on the top, and no one even looks at you funny. If you're into cowboy action shooting, one full-size golf bag can carry your whole competition rig with ease(one shotgun ,one rifle, two pistols, and ammo/leather for all). The only downside is that people might start thinking you play golf...which might be good or bad, depending on how you look at things.
