More a "feature" than a bug. The "fired" bonus represents the visual effect of tracer ammo to adjust aim in sustained fire, so "firing" with jammed guns shouldn't give the bonus in subsequent turns.

http://www.youplay.it/play/bm_GameMove.asp?GameID=798701

31. gugliandalf fired at Doorstop, distance 1 with deflection. 0 points. No relevant damages. (Base:7,Stb:+1,1Gun:-2,Defl:-1,Tail:+2,Long:+1,Jammed).

32. gugliandalf fired at Doorstop, distance 1 with no deflection. 0 points. No relevant damages. (Base:7,Stb:+1,1Gun:-,Tail:+2,Fired:+1,Long:+1,Jammed).

33. gugliandalf fired at Doorstop, distance 1 with no deflection. 9 points. Damage R (Base:7,Stb:+1,1Gun:-2,Tail:+2,Fired:+1,Dice:+2).