Are there any weapon attachments hidden in the beta?
Here is the full list of mods based on the text data. I don't have time today to check these properly in the game so it is possible some are not fully implemented.
Iron Sights - Standard-Issue Sights
HCOG - 1.85x Zoom Holographic Gunsight
Holosight - 2.1x Zoom Holographic Gunsight
AOG - 2.4x Zoom Advanced Gunsight
4.5x Zoom Scope - Mid-range magnification scope
6x Zoom Scope - Long range magnification scope
Extended Magazine
Extended Clip
High-Capacity Drum
Extended Ammo Capacity
Leadwall - Disperses pellets over a larger area
Suppressor - Reduces noise and muzzle flash
Enhanced Targeting - Accelerates lock-on rate and increases range
Scatterfire - Increases rate of fire, decreases accuracy of R-97 Compact SMG
Stabilizer - Reduces sway when looking down scope
Match Trigger - Ignores fire rate limit
Starburst - Hemlok BF-R 5 round burst
Counterweight - Maintains higher accuracy while moving
Slammer - Increases rodeo damage
Burst Fire - Fires three rounds
Rapid Fire - Converts the weapon to a semi-automatic rocket launcher with a high rate of fire.
Accelerator - Rate of Fire increases while holding fire
Instant Shot - No build-up, but lower max damage
Capacitor - Deals increased damage, but must be charged to full
Mine Field - Converts the weapon to fire ballistic mines, which plant into the ground when fired, and then detonate using built-in proximity fuses.
Automatic Fire - Fires continually without releasing the trigger
Electric Rounds - Deals increased damage to shields
Explosive Rounds - Deals damage around the point of impact
Fast Reload - Reduces time to reload
Guided Targeting - Direct the flight of the Archer missile
High Density Explosive Rounds - Heavy, powerful explosive grenades
Hydraulic Launcher - Propel grenades further by holding down the trigger
Impact Fuse - Explodes on contact with any surface
Mortar Shots - Lobbing projectiles, larger explosion
Overcharge - Drains shield to accelerate charge
Powered Magnets - Increased magnetic range, reduced damage
Power Shot - Higher max damage, longer charge
Quick Shot - Faster charge, lower max damage
Sniper Assist - Scope displays information about target
Splitter - Lightning arcs to additional targets when it splits
Scatter Shot - Widens the cone of fire
Broadside - Narrows the cone of fire
Recoil Compensator - Reduces recoil while firing
Rolling Rounds - Grenades slide further
8X Zoom
10X Zoom
12X Zoom
Automatic Fire Burn Card - Rapid Fire Shotgun
Semi-Automatic - Fires 1 shot at a time
Splasher Rounds - Anti-Personnel Rounds
Stabilized Warhead - Increased precision, slower rate of fire
Tank Buster - Slower, more powerful missile. Explodes after short delay
Titanhammer Missile - Devastating anti-Titan Missile
Twin Slug - Holds two slugs per magazine, but fires them simultaneously
Match Trigger Burn Card - Ignores fire rate limit