SMLE Mk III Infantry. 90 Damage with body hit. 1 Shot kill to head, 2 Shots body (i think extremities, chest shots may 1 shot kill depending on range). If you hit someone, and a teammate finishes that dude off, you get an assist counts as kill. If you hit someone who is wounded, 1 shot kill.
Super OP prolly gonna get nerfed but its all i run, since the starting assult and medic guns are inaccurate, slow and require you to empty your gun just to get one kill