So I'm almost done with a little 5.5" 9mm AR pistol build. I have the law tactical folding stock adapter on it as well. Still waiting on barrel and hand guard which should bring it to a length of 15"-16" with the stock folded. I used to have the folding stock adapter on my 8.5" 300 blackout and I was able to carry it pretty comfortably in a standard size dakine backpack I had laying around. I'm building this pistol as a little EDC truck gun or something I can throw in a small backpack and take where I please. My issue with the dakine backpack is that it doesn't have much support and it has a good bit of extra room so my AR would just bounce around in there a little more than I'd like. I was hoping someone might have a suggestion for a new little backpack that I can stuff a 15" AR into and carry comfortably. I'm not looking for anything that screams I'm carrying a gun but a little extra tactical BS is fine with me. What I really want is a more supported but smaller backpack. Maybe something with some sort of velcro or tactigami something or other that would hold the gun in place. I like the vertx edc transit sling bag but I need two straps. Well I don't need them but I'd really like to have them. Alright, all suggestions are appreciated. Thanks.

Look at instrument cases.

Great suggestions, though I'm really looking for more of a double strap backpack style edc bag. I want to be able to keep it on me while on my motorcycle and be able to throw it on and off while hopping in and out of the truck. Just a small tough backpack that will support a 15" folded AR. Like I said I'm still waiting on the barrel and hand guard but it will be pretty similar to the ones Gorilla arms has been building.

https://www.google.com/search?q=gorilla+arms&source=lnms&tbm=isch&sa=X&ved=0ahUKEwj3rMjQ0PnTAhUoqVQKHXquCmcQ_AUICigB&biw=1440&bih=803#tbm=isch&q=gorilla+arms+ar+9mm&imgrc=Q10pVbNRdyavfM:

5.11 Select Carry sling bag is meant for an MP5. It holds my 10 inch AK pistol perfectly.

Its not too tactical if you remove the 5.11 tags.
No external molle to give it away.

Again, looking for a double strap. Not a sling bag, otherwise I'd go with the vertx edc commuter sling.