- The Underbarrel Weapons themselves, plus the secondary versions of their ammo items, now have infiltration costs. The utility versions use the default utility item cost and didn't need to be set up separately.

- Conventional Underbarrels drop from timed loot, and can also be built in Engineering after finishing each of their respecting Proving Grounds projects, much like other attachments in LWOTC.

- Costs and requirements have been adjusted for Magnetic and Beam tiers as well. They are cheaper than before. Underbarrel Shotgun upgrades are gated behind Gauss Weapons and Alloy Cannon, and Underbarrel Grenade Launcher and Underbarrel Flamethrower upgrades are gated behind Plasma Grenade and Advanced Grenades. You will also need one of the previous tier of Underbarrel in order to make the next tier.

- The Underbarrel Shotgun has a new range table. As inaccurate as a LWOTC shotgun at range, and as accurate as a LWOTC SMG up close. Their damage has been buffed, mainly for Mag and Beam tier, to match that of full size shotguns in LWOTC, although with lower max damage. Crit chance is also lower than a full size shotgun, and they can't be used for skills like Trench Gun or Street Sweeper that require a primary shotgun. All Underbarrel Shotguns now do a very small amount of environmental damage (1).

- Underbarrel Grenade Launcher range (other than Beam tier) and environmental damage has been nerfed, while damage has been buffed for Mag and Beam tiers. Beam tier uses Blaster Launcher targeting.

- Underbarrel Flamethrower cone size, both length and width, have been nerfed to 1 tile less than the LW Gauntlet Flamethrower (without Incinerator) for Mag and Beam tier. Conventional tier is even smaller than that. Beam tier has 1 point of Shred now to reflect the acidic nature of the chemical mix it uses. Underbarrel Flamethrowers no longer do any environmental damage, but still can set terrain on fire which can lead to terrain features crumbling over time.

- Underbarrel Flamethrowers only have 1 charge, and the Underbarrel Flamethrower Tank item only grants 1 additional charge. There is also an Underbarrel Flamethower Tanks item for the secondary slot that grants 2 additional charges.

- The Quickburn skill now can affect all 3 tiers of the Underbarrel Flamethrower.

- The Fastball skill can now affect all 3 tiers of the Underbarrel Grenade Launcher.

- The Underbarrel Shotgun Ammo for the secondary slot now also makes firing the Underbarrel Shotgun non-turn-ending.

- Utility slot versions of underbarrel ammo items now have 1 weight each.