All the guns I use AND have to upgrade after 2 weeks:
Bar (PK, Basing, When sparring against other BARS, Shipkas etc)
Souzien (Tag Team Spar gun, Spar)
PBP (Basing in small basses)
Luger (Spar, occasionally in base)
Sten (most used Spar gun, beastly in Spar)
M4 (another spar gun to make it 'equal' against other M4 users at times)
Artilery Cannon (Basing ESPECIALLY in BBZ, Trolling in Spar)