The item ID for "Berserker" Grenade Launcher (Rare) is 18272
This is the spawn command to give yourself "Berserker" Grenade Launcher (Rare) in The Front.
Copy the command below and paste it into the server admin console to obtain. You can open the console by pressing the backtick (`) on your keyboard.
If playerID is empty, the item will be given to yourself.