I was thinking it could be a PDA and if you have the Gunslinger there could be a Mini Drone thing and you could upgrade if you are not usng the gunslinger. If equip the PDA while the gun is flying you can press R and it comes back to you. When you do that or when you first put it down you can upgrade it if you are not using gunslinger. You will have all three stages to with each one making it faster, stronger, and harder to destroy. It could replace your sentry. If you have The Wrangler you can control where it flys and while you do that you can press R any time and it returns.