If you're tired of projectile lag, building a roblox raycasting script gun is the best way to get instant hit detection in your game. Let's be honest, using physical parts for bullets is fine for a slow-moving rocket launcher, but for a fast-paced shooter, it's just not going to cut it. You need something that hits the target the exact millisecond you click, and that's where raycasting comes in.
Why raycasting beats physical bullets
When I first started out, I thought making a gun meant spawning a tiny sphere, giving it some velocity, and checking if it hit a wall. It sounds logical, right? But the problem is that Roblox's physics engine has to do a ton of work to track that tiny moving object. If your bullet is moving at 1,000 studs per second, it might actually skip right through a thin wall or a player's head between frames.
Raycasting doesn't have that problem. Instead of moving an object through space, it basically draws an invisible mathematical line from point A to point B instantly. It asks the engine, "Hey, if I fired a laser in this direction, what's the first thing it would hit?" The response is immediate, and it tells you the exact position, the material, and even the specific part it struck. It's faster, cleaner, and way more reliable for competitive gameplay.
Setting up the basics
Before we dive into the code, you need a basic setup in Studio. You'll want a Tool object in your StarterPack. Inside that tool, you'll usually have a part called "Handle" (or a model if you're fancy), a LocalScript, a Script, and a RemoteEvent. Let's name the RemoteEvent "ShootEvent" so we don't get confused.
The RemoteEvent is the most important bridge here. Since we're dealing with an online game, the player's computer (the Client) knows where they are clicking, but the server (the Server) is what actually needs to deal out the damage. If you do the damage calculation on the client side, exploiters will have a field day giving everyone instant headshots from across the map.
The logic behind the ray
To make a roblox raycasting script gun work, you need two main pieces of information: the Origin and the Direction.
The Origin is usually the tip of your gun barrel or the position of the player's camera. The Direction is where the shot is going. Most people find it easiest to use the Mouse.Hit.p (the position where the cursor is pointing) and subtract the gun's position from it. This gives you a vector pointing right at the target.
Once you have that vector, you multiply it by a large number—like 500 or 1,000—to determine the gun's range. If you don't multiply it, your "ray" will only be about one stud long, which isn't going to hit anything unless you're literally touching the enemy.
Writing the LocalScript
The LocalScript handles the user input. It listens for the click, calculates where the mouse is pointing, and sends that info to the server. It looks something like this:
You connect a function to the Activated event of the tool. Inside that, you grab the mouse position. I personally like to use UserInputService or just the Player:GetMouse() method because it's straightforward. You send that position through your ShootEvent using :FireServer(mousePosition).
Don't do anything else here yet. No sound, no flashes—let's get the hit detection working first.
Handling the server-side logic
This is where the magic happens. Your server-side script is waiting for that ShootEvent to fire. When it receives the signal, it performs the actual raycast.
Roblox uses a function called workspace:Raycast(). It takes three arguments: the origin, the direction (and distance), and an optional RaycastParams object.
Pro tip: Always use RaycastParams. You need to create a new RaycastParams object and add the player's character to the FilterDescendantsInstances list. If you don't do this, the ray will hit the player holding the gun the second it's fired. You'll be wondering why your gun never hits anyone, only to realize you've been "shooting" your own arm the whole time.
Making it look good with visuals
Since raycasts are invisible, a gun that just clicks and makes health bars go down feels pretty boring. You want to see a tracer, a flash, or at least some spark where the bullet hits.
To do this, you can create a "beam" or a stretched-out part to act as a tracer. Since the raycast gives you the exact Position of the hit (the Result.Position), you can create a part that spans the distance from your gun barrel to that hit point.
I usually put the visual stuff back on the client side. Why? Because if the server handles the visuals, there might be a slight delay for the player who fired. If the client handles the visual part, the gun feels "snappy" and responsive, while the server quietly handles the math of whether or not someone actually got hit.
Dealing damage and checking for humanoids
Once your ray hits something, the RaycastResult will return an object called Instance. You need to check if that instance is part of a character. The easiest way is to use hit.Parent:FindFirstChild("Humanoid"). If it finds a humanoid, you can call :TakeDamage().
Wait, there's a catch. Sometimes the ray hits a hat, a tool, or a stray part inside a character model. You might need to check the parent's parent as well, or use a recursive function to find the humanoid. But for a basic roblox raycasting script gun, checking the immediate parent is usually enough to get you started.
Common mistakes to avoid
One thing that trips up almost everyone is the "direction" math. Remember: it's (TargetPosition - OriginPosition). If you flip those, your bullet will fly backward behind you. I've done it more times than I'd like to admit.
Another big one is not limiting the fire rate. If you don't put a wait() or a "debounce" in your script, a player with an auto-clicker will fire 500 rays a second and crash your server. Always put a small cooldown between shots. Even 0.1 seconds makes a massive difference in stability.
Security considerations
As I mentioned earlier, never let the client tell the server how much damage to do. If the client sends a message saying "I hit this guy for 100 damage," a hacker will just change that 100 to a billion.
The client should only send the intended target or the mouse position. The server should then verify if that shot was even possible. For example, if the player is in the spawn room but trying to shoot someone across the map through three walls, your server script should probably ignore that request. Raycasting on the server is a built-in way to verify line-of-sight.
Wrapping things up
Building a roblox raycasting script gun might feel a bit intimidating compared to just throwing a part with a "Touched" event, but the results speak for themselves. Your game will feel more professional, your hits will be more accurate, and your players won't be complaining about bullets lagging through walls.
Once you get the hang of the basic workspace:Raycast() workflow, you can start adding cool features like wall penetration, ricochets, or even gravity-affected drop (though that gets into some more complex math). For now, just focus on getting that origin and direction right, and don't forget to filter out the shooter! Happy coding, and go make something awesome.