You walk into a cave to escape the rain, and you question where you are, then, you notice a faint melody coming from a passage in the cave, you cant understand the language of the music, but its alluring, and you decide to walk down the passage. After around five minutes of walking, you reach the end of the passage, and you see a large room, and in that room, you see strange flags, a chair with the contraption playing the music next to it, a large piece of an unknown metal with a large eagle, and a strange object on a table. The object has buttons, a confusing handle, and a weird looking chain with brass and lead on said chain, and you decide to pick it up. Upon closer inspection, you can make out a few weird symbols on it, and strange writing that you can barely make out, and it says, "Auf dass wir niemals vergessen mögen" , and you attempt to pronounce it in common, and out of the corner of your eye, you see a man with a strange looking uniform put his arm around your back, and he says in a strange language, "Das wird spaßig", then disappears, and  you feel a deep chill down your spine, and you hear "Nice place" in your head.

 

The player, unlike the MG-42 cannot find parts for "The Shnitz's Buzzsaw", but you can craft them.

It takes 1 main action to reload a 50 round drum, 1 turn to reload a 75 round drum, depending on the amount of ammo in a belt (standard amount is 200 rounds), it can take between 1 to 5 turns.

The DM/GM can decide wether the player has proficiency (or can even get proficiency), and can decide if the player can practice with it (takes 50 hours of practice to gain proficiency).  

If combat is initiated while a player is holding The Shnitz's Buzzsaw, roll a D100, If it lands on 19, 25, 42, 50, 75, or 100, The Strange Officer appears and attempts to charm the closest hostile (+5 CHA mod), if the hostile is charmed, they get transported to the ethereal plane and the officer sits down and hums, if the hostile is not charmed, they take 1D6 psychic and the officer disappears. If you roll a 69, you will get transported to a lower plane, and get transformed into an Incubi/Succubi, and then comes back to the battlefield. 

Attacks

• Full auto: The player empties the belt/drum, if the player fired between 5-50 rounds, it does 2D12 proj+1D10 blast, if they fired between 50-75 rounds, it does 2D12+1D10 blast. If they fired between 75-150 rounds, it does 4D12+2D12 blast, if they fire more than 150 rounds without stoping, roll a D4, if it lands on a 1, the barrel breaks. 
• Bursts: choose between a 5 round burst (1D10 proj+1D10 blast), a 15 round burst (1D12 proj+1D10 blast), or a 25 round burst (2D12 proj+2D12 blast), If proficient, the player can combo 2 bursts.
• Butt stroke: the player uses the Buzzsaw as a melee weapon, hitting the hostile with the butt stock,  dealing 1D10 of damage, roll a D6, if it lands on a 4, a piece breaks, roll a D4, the corresponding piece breaks and needs to be replaced or repaired and the Buzzsaw can't be used until repaired.

Crafting

• 7.92 Explosive Mauser bullets (20): 2lbs brass, 1lb lead, 1lb gunpowder
• Belt (50 links): 5lbs steel 
• Drum (50): 3lbs steel 
• Drum (75): 4lbs steel 
• Spare barrel: 5lbs steel
• MG-42 body: 15lbs steel, 5lbs wood, 3lbs silver
• MG-42 internals: 5lbs steel, 3lbs, silver, 
• MG-42 charging handle: 2lbs steel

Misc Info. 

• If the player fires 200 rounds continuously, the barrel will break, and it will take either 2 turns (DEX 13 or lower) or 1 turn (DEX 14 or higher) to change it out, if the player has a DEX of 18 or higher, it only takes 1 main action 
• The player can increase the belt length by 50 rounds (max 1000), but this will increase the time it takes to reload (1 turn per 200 extra rounds) 
• If the player goes prone and deploys the bipod, it gives them advantage on attack roles and speeds up reload times (1 bonus action for 50 round drum, 1 main action for 75 round drum, and 1 turn for a belt change (200 round belt).
• MG-42 Barrel (1) MG-42 Body (2) MG-42 Internals (3) MG-42 Charging handle (4)

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: Charisma Score, Damage, Combat, Cursed, Range, Two-Handed, Ammunition (Firearms), Burst Fire, Reload, Slow