One of the parts for the AR-15 that's often ridiculed for merely existing is the non-pistolgrip, to remove a "scary" feature from it and let it get by onerous gun laws. I finally came up with a use for one outside of someplace where it's used only because the law forces it.
Over the years, I've saved myself and bailed my party from many a bad situation with an SMG or assault rifle under my character's coat. Realistically, the extensive height of a modern sporting rifle renders this a difficult proposition, even with a large, loose coat. I've pulled it off quite effectively with my S2k under my duster, but I could feel the grip desperately attempting to print.
While pondering the pistol "wrist brace", along with my bf playing some Payday 2 beside me, it came to me. A lower cap magazine, a non-pistolgrip grip, and the wristbrace gives a slimline gun. Add in a shoulder holster or single point sling set to keep the gun at your side, and it should vanish under nearly any coat. When not in the gun, magazines actually don't add that much bulk for a couple, it's only when they're stuck out the bottom at 90 degrees they really add to the size.
Everyone keeps whining about people open carrying rifles. Maybe they'll whine less if I carry mine under my coat? Hey, they SAID they didn't want to see it!