While pistols are by and large the weapon of choice for sneaky fraggers, don't necessarily count out long arms or automatics if you're looking for that to be part of your guy's shtick.
For instance, there are Machine pistols for automatics, which are 4P weapons with auto-fire capability for increased damage. Those have a concealment modifier of +2, which means that, under a long coat, it's a straight-up test between your Palming + Agility and their Intuition + Perception.
On the long arm front, there's the Defiance T-250 sawed off. It starts off with a concealment modifier of +2, does 5P -1AP and uses heavy pistol ranges (and choke rules.) Throw a sling on it, and now it's 0 conceal, just like a heavy pistol. In fact the only difference between it and a heavy pistol at this point is that it's a 7 round magazine fed weapon that can use specialized shotgun rounds, which is pretty useful for breaching doors with shock-lock rounds.
Picture a belt of assorted shells. You have Stick-'n'-shock, Explosive, Ex-Explosive, Sub-sonic, Shock-lock, Fletchette, Slugs, Double-aught buckshot, APDS, everything you could need for any situation. Situation arises, you take a Complex action to load [Agility] rounds into the gun, and those shells are the ones that come up first.
So, you're sneaking about where you're not supposed to be when you come across a lone ganger doing a line of Novacoke off a fresh corpse. You load in a couple of sub-sonics just to make this whole thing whisper-quiet. Pam. Pam. Ganger is toast, but there's something sparkling in your vision! A spirit materializes!
You go, "Oh no! A Guh-guh-guh-GOHST!" break for cover and slot two stick-n-shock rounds into your magazine.
Ghost rounds the corner right into your held action to fire two shockers right into its puss. That ghost won't be haunting any more amusement parks. You walk up to the door to the warehouse where the macguffin is stored, but, oh what the hell, the door is barred from the inside. No amount of hardware or lockpicks is going to break the hinges off this sucker. In go the shock lock shells and splat go the hinges. Subtlety be dammed, if a hobo with a shotgun can clean up the streets so well, they better watch out when a runner with a shotgun shows up to the party!