The 9mm is a ranged weapon and the worst gun in Devast.io. It can be unlocked at Level 7 for 1 Skill Point. For the first gun, it's also the weakest and easiest to craft, as it requires 6 Junk and 9 Shaped Metal. It uses 9mm Parabellum ammo (Bullet). When the materials are gathered, the weapon is crafted on a Research Bench.
The 9MM can be found in abandoned houses, making it obtainable even in early-game. However, the gun is useless unless the proper ammo is found as well. If found without ammo, craft a Wood chest and store the gun there.
It is not recommended to craft a 9mm. 9 shaped metal is a lot, and upgrading to desert eagle is easier. If you need a ranged weapon, a crossbow isn't that bad; it does 50 damage, its ammo is cheaper, and the weapon itself is also cheaper.
To kill one player you need to hit him 10 times (10*28=280). It is also good that you have 20 magazines and therefore you can afford to make mistakes.