Todd, I have a JRC 9mm that is a breakdown. The barrel screws into the stock/receiver with a AR style stock. Also have a 10/22 take down. Also have a Anderson lower 556 AR 16" barrel, that I put into a 10/22 take down case. Take a look at both their websites. They don't look like "guns", except for the 10/22 red logo on the bag. But only a gun owner would likely know that and not bother you. I also have a Anderson lower 556 pistol, 11.5" barrel, that needs a "backpack". Let me know when you have some designs.
Also, you may want to look at "holsters" for the AR pistols. In Texas you MUST have it in a holster if you OC. Other States may have the same or similar requirements. I won't OC unless it is neighborhood watch time. I would prefer a "cross chest holster".
Marcus