Antitank Rifle

The cutting edge of military technology. A large caliber anti-tank rifle meant to punch through light vehicles, and disable the treads on true tanks. Personal armor doesn't stand a chance. Too powerful to scope - throws optics off violently. 

You must spend an action to ready this weapon for use, deploying the bipod either onto low cover or the ground (requires user to be prone). Firing without first deploying the weapon incurs disadvantage on the shot, and the weapon cannot be reloaded when not deployed.

Reduces target AC by 10, must be reloaded after every shot. Deploying weapon removes user's Dex-bonus from AC. Regular roll modifiers also apply.

Carrying grants disadvantage to Dex saving throws and reduces movement by 5ft.

(Extremely) Loud, Reload (1 shot)

2d12+4 damage

Ammunition is extremely expensive, 5GP/shot

100/600 Range

Swinging like a melee weapon deals 1d6 bludgeoning damage. 

It’s up to you to decide whether a character has proficiency with a firearm. Characters in most D&D worlds wouldn’t have such proficiency. During their downtime, characters can use the training rules in the Player’s Handbook to acquire proficiency, assuming that they have enough ammunition to keep the weapons working while mastering their use.

Notes: Ranged Weapon Attack: Piercing, Damage, Combat, Range, Two-Handed, Ammunition (Firearms), Reload, Sap