1. Open gamecih then Shadowgun
2. While in game, notice the amount of ammo you have in a clip. If just starting out, you should have 30//150.
3. Bring up the gamecih menu, search > input number, and search for 30
4. Go back into the game and shoot a bullet. I shot exactly one, so I'm left with 29
5. Search 29 and you should get a bunch of lines starting with 0's and a couple with 4's.
6. Select one of the lines starting with 4, type 30 and lock it. If it doesn't change the value back to 30, unlock it and try a different line.
(note - the line seems to change each attempt, so there is no set line beginning with 4. It seems to be the 2nd "4" entry, but needs further testing)
Enjoy never reloading.