In the case of the gun creating a portal out of combat to move around, the gun is just a focus. It you just teleport yourself it would look like
Teleportation 6", MegaScale (1" = 1 km; +1/4) (15 Active Points); OIF (-1/2)
If you need a gate to move other people around or let water through it might look like this
Teleportation 6", MegaScale (1" = 1 km; +1/4), Usable By Other (+1/4), Area Of Effect (One Hex; +1/2), Continuous (+1) (36 Active Points); OIF (-1/2), Gate (-1/2)
* Remember gates go both ways!
Spend 4 points to set up four fixed locations. That's a nice array (like his Armory, the bottom of a lake, an empty supermax prison cell reserved for "night deposits" and his favorite food store).