I am sick of having to quit matches and restarting searches due to being stuck with slayer pro. I am trying to get my suppressor and storm rifle commidations mastered at the moment (I have assult rifle completed already). I tried Infinity Slayer, Big Team Infinity Slayer, and Rumble Pit. Any suggestions on what to do or what to try?
Go play any objective gt, There’s always some noobs using those.
especially on extraction and KotH
Ive mastered all weapons…regicide is the place to go for alot of them, including the ones you speak of…
Heh…you think those are hard commendations? Boy, are you in for a big surprise when you start mastering the Plasma Pistol. I personally haven’t started, but many of the veterans here could tell you spectacular horror stories about it. O.O
Anyway, Regicide seems to be the go to for all loadout weapons, and some heavies, too. Basically, just like Dadiola said. 
Oddball, KotH, and Regicide.
Regicide is best. Don’t be that guy in Oddball or KotH who ignores the game type and plays slayer to pad his stats. 
Multi-Team.
Regicide or Oddball in multi team always people on low shields easy clean up kills I would go to one of those two for commendations.
Regicide!!! If you go into an objective gametype with the sole purpose of statting certain weapons, it ruins the game for your team mates. Regicide offers plenty of enemies and many close quarters combat. Use dexterity for quick reloads and lead with grenades on enemies for easy clean ups with your automatic weapon.
I agree that if you don’t have the good sense to play the objective then you should stay the heck away from objective playlists. However, it is quite difficult to stat pad using an automatic weapon without getting close to the objective first.
Regicide, KotH, and Oddball. Sometimes Action Sack, depending on the map.