Ok here is a confirmed weapon list for medium/light and what unlocks them. The Four Challenges are Parkour This, Be More Objective, Escort Duty, and Tower Defense.
Medium Weapons
Assault Rifles
•Gerund- Unlocked at start
•Euston- Unlocked at start
•FRKN-3K- Tower Defense “1 star”
•Rokstedi- Unlocked at start
•Rhett- Unlocked at start
Grenade Launcher
•Lobster- Use More Objective “1 star”
Shotgun
•Mossington- Unlocked at start
Light Weapons
Long Rifles
•Drognav- Unlocked at start
•Barnett- Parkour This “1 star”
SMG’s
•Galactic- Unlocked at start
•Tampa- Unlocked at start
•Bulpdaun- Be More Objective “2 star”
•Kross- Unlocked at start
•CARB-9- Unlocked at start
Sidearms
Semi-auto’s
•Kalt- Unlocked at start
•Sea Eagle- Unlocked at start
•Tokmak- Unlocked at start
Revolvers
•Ritchie- Use More Objective “1 star”
•Caesar- Psycho Pre-Order DLC
Machine Pistols
•Belgo- Parkor This “1 star”
•Hockler- Spec-Ops Pre-Order DLC
Assault Rifle Attachments and what unlocks them
Front Attachment
•Silencer- Parkor This “2 star”
•Soda Can/ArkTactical Silencer- Pscho Pre-Order DLC
•Four-Vent Muzzle Brake- Escort Duty “1 star”
•Six-Vent Muzzle Brake- Unlocked at start
•Down-Vent Muzzle Brake- Unlocked at start
•Duel-Vent Muzzle Brake- Unlocked at start
Bottom Attachment
•Speed Sling- Be More Objective “2 star”
•Grenade Launcher {AKA NOOB TUBE}- Tower Defense “1 star”
•Front Grip- Parkor this “1 star”
Magazine Attachment
•Standard AR Mag- Unlocked at start
•High-Capacity Magazine- Tower Defense “2 star”
•Duct-Taped Magazine- Be More Objective "1 star
•AR Drum Magazine- Escort Duty “2 star”
Top Attachment
•Iron Sights- Unlocked at start
•Adjusted Iron Sights- Tower Defence “1 star”
•Greeneye Scope- Spec-Ops Pre-Order DLC
•COGA Scope- Escort Duty “1 star”
•D-Flex Red Dot Sight- Escort Duty “1 star”
•C-U-Gone Red Dot Sight- Unlocked at start
•YeoTek Red Dot Sight- Unlocked at start



