The new Ares Armor Low Profile Arsenal (LPA) Bag gives you a fairly discreet way to carry guns and support gear.
The LPA features 1000D nylon construction and closed cell foam padding throughout. It has three padded sections in the main compartment that can keep your firearms from knocking into each other during transport. It also has a removable padded spacer for pistols. In addition to the firearm storage, there is plenty of additional organization options for smaller items like magazines, hearing protection, and all the other stuff you end up toting to the range.
http://www.musiciansfriend.com/accessories/musicians-gear-3-4-size-acoustic-guitar-gig-bag
I’ve been getting away from “discreet” bags for the last few years, b/c frankly most of these bags still scream “GUN” to me…like a fanny pack does. Guitar soft gig bags come in a lot of different configs and nobody thinks twice about me carrying it around, unless they’ve seen El Mariachi too many times. Tennis racquet cases work well too, you just look a little weird going to a restaurant etc with one. Looking forward to hearing from others on what they use. Thnx!