ARC-920 Railgun "Whiplash"

A sleek, white rifle with a long space of emptiness separating the top and bottom barrel. As you press your finger against the trigger, you feel as though their are several motors in each barrel, spinning. As they spin, the display showing a number on it pops open, revealing a tube to insert chunks of hard substance. When the rifle is loaded, the display clasps down, counting the number of shots you have. After around 5 seconds, the weapon finishes charging, and letting loose a slug of whatever hard substance it's been loaded with.

You have a +3 bonus to attack and damage rolls made with this magic weapon.

Charge Up Time.  This weapon takes the wielder's action and bonus action to make a Ranged Weapon Attack with. This requirement can be substituted by using both attack actions, if a character has access to them.

Railgun Round. This weapon can be loaded with any metallic substance as long as it is no larger than 40mm x 50mm (the dimension of a proper slug for this weapon) and no smaller than 30mm x 30mm. When using regular slugs instead of the designated ammo, this weapon's damage die is reduced to a d8, instead of a d12.

Disorienting Shot. Whenever you hit with a Ranged Weapon Attack using this weapon, every creature within 5ft. of the target must make a (save DC15) Dexterity Saving Throw or gain the "Dazed" condition until the start of their next turn, or the next roll they make for either of the effected stats.

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: Bonus: Magic, Replace Damage Type: Bludgeoning, Ignore Weapon Property: Ammunition, Damage, Combat, Range, Two-Handed, Ammunition (Firearms), Reload, Sap