I think one of the best is the future rifle up1
1. Very high cartilage supply
2. High fire rate
3. Extremely accurate with a 4x zoom.
Recommended maps by me: Ants life (because of the zoom) , and Campaign (high damage to monsters and fast shooting
Also the Automatic Peacemaker because of the very high cartilage supply and fire rate
Recommended maps: Enclosed ones because it is not accurate