There is no set templates for guns.
Just include all these sprites, plus added ones in case you have special functions for your gun:
1. Right idle. (Normal pose facing right.)
2. Left idle. (Normal pose facing left.)
3. Up idle. (Normal pose facing up.)
4. Down idle. (Normal pose facing down.
5. Right reload. (Gun without the clip, facing right.)
6. Left reload. (Gun without the clip, facing left.)
7. Bullet/Laser right. (Bullet facing right.)
8. Bullet/Laser left. (Bullet facing left.)
9. Bullet/Laser up. (Bullet facing up.)
10. Bullet/Laser down. (Bullet facing down.)
11. Clip. (Clip alone without gun. Also gives artists a chance to add a semblance of bullets protruding from the top.)
And that is your basic gun sprite sheet's components.
Sorry if I missed anything critical.
I also know Zone guns might be alot different (being more futuristic), but that should apply.