Getting a roblox bullet drop script physics system to feel "right" is a bit of a rite of passage for every dev making a shooter on the platform. If you've spent any time playing big titles like Battlefield or even some of the more hardcore shooters on Roblox like Phantom Forces, you know exactly what I'm talking about. You don't just point and click; you have to account for distance, aim slightly above your target, and time your shots.
It's a massive jump in quality from the basic "hitscan" weapons where the bullet travels instantly in a perfectly straight line. While hitscan is fine for arcadey games, it doesn't give players that satisfying "long-shot" feeling. If you want to build something that feels tactical, you need to dive into the world of actual projectile physics.
Why hitscan usually isn't enough
Most beginners start with hitscan because it's easy. You click, a raycast shoots out, and it tells you instantly if you hit something. There's no travel time and no arc. But the moment you try to create a sniper rifle that needs to hit someone across a massive map, hitscan starts to feel cheap. It removes the skill gap involved in leading a target or compensating for gravity.
When you implement a roblox bullet drop script physics system, you're essentially simulating a physical object moving through space over time. This means the bullet actually exists for a few seconds, moving forward while gravity pulls it down. It makes your gunplay feel grounded and gives your weapons a unique personality. A heavy sniper might have less drop than a 9mm pistol, and that's where the fun begins for the player.
The core logic behind bullet movement
To make this work, we have to stop thinking about a single raycast and start thinking about a series of small raycasts. If you try to just move a Part with Velocity, Roblox's built-in physics engine might struggle with high-speed projectiles. Small parts moving at 1,000 studs per second often phase right through walls because they move too fast for the collision engine to catch them between frames.
The solution is to use RunService.Heartbeat or RunService.RenderStepped to update the bullet's position every single frame. In each frame, you calculate where the bullet should be based on its current velocity and the pull of gravity, and then you draw a raycast from its old position to its new one. If that raycast hits something, you trigger your damage logic. If not, the bullet keeps flying.
Setting up the math for gravity
Gravity on Roblox is usually set to around 196.2 studs per second squared by default. That's a bit high for realistic bullets, but it's a good starting point. The basic formula you'll be looking at involves updating the bullet's velocity on every frame.
Essentially, you take your bullet's current velocity and subtract the gravity force multiplied by the time since the last frame (deltaTime). This makes the bullet "sink" as it travels. You don't need to be a calculus expert to get this right; it's just basic vector addition. You have a forward vector (the direction the gun is pointing) and a downward vector (gravity). When you mix them together over time, you get that beautiful curved trajectory.
Creating the main loop
The "heart" of your roblox bullet drop script physics is going to be a loop. Instead of using a while wait() do loop—which is notoriously unreliable—you'll want to hook into RunService. This ensures your bullet physics are synced with the game's frame rate.
Inside this loop, you'll store variables for the bullet's current position and its current velocity. Every frame, you calculate the "displacement." The displacement is just the velocity multiplied by the time elapsed. You then perform a workspace:Raycast from the current position to the new calculated position.
If the raycast returns a result, you've hit something! You can then spawn a bullet hole decal, play a sound, and stop the loop. If it doesn't hit anything, you update the position variable to the new spot and repeat the process for the next frame. It's a very "frame-by-frame" way of thinking, but it's the only way to ensure the bullet doesn't skip over a player's head because the frame rate dipped.
Handling performance and lag
Now, if you have 30 players all firing machine guns at the same time, you might start to worry about performance. Calculating dozens of raycasts every frame can get heavy if you aren't careful. One of the best ways to handle this is to do the heavy lifting on the client side for the person firing the gun and then have the server validate the hits.
For the visuals, you definitely want to handle those on the client. Creating a physical Part for every bullet can be a bit much for the server to handle. Instead, use a simple Beam or a Trail and update its position locally. The server only needs to know the starting point, the initial velocity, and the timestamp. This way, the server can "reconstruct" the bullet path to check if a player actually hit their shot without having to render fancy tracer effects for everyone.
Adding bullet drag for extra realism
If you really want to go the extra mile with your robshot bullet drop script physics, you can add "air resistance" or drag. In real life, bullets lose speed the further they travel because of air. In Roblox, you can simulate this by slightly reducing the bullet's velocity on every frame.
It's a simple addition to your math. Just multiply the velocity by a small decimal (like 0.99) every frame. This makes long-distance shots even harder because as the bullet slows down, gravity has more time to pull it toward the earth. It creates a much more dramatic drop at the end of the bullet's flight path, which is something sniper enthusiasts really appreciate.
Visualizing the bullet path
Let's talk about tracers. Nobody likes invisible bullets. Even if your physics are perfect, players need to see where their shots are going so they can adjust their aim. Using the Trail object in Roblox is usually the easiest way to go. You attach it to a small, invisible part that follows your calculated physics path.
Another pro tip: don't start the tracer right at the tip of the barrel if the player is moving fast. Sometimes it looks better to offset the visual start point slightly so it doesn't look like the bullet is "lagging" behind the gun.
Dealing with common bugs
One of the most annoying issues you'll run into is the bullet hitting the person who fired it. Because the bullet starts at the gun's muzzle, and the muzzle is usually very close to the player's character, the first raycast might immediately detect the player's own arm or torso.
To fix this, you need to use RaycastParams. You can create a new RaycastParams object and add the player's character to the FilterDescendantsInstances list. This tells the physics engine to ignore the shooter entirely. You should also probably ignore the bullet itself (if you're using a physical part for the tracer) to avoid the bullet "hitting itself" and stopping mid-air.
Why custom physics beat the "BodyVelocity" method
Some people try to use BodyVelocity or LinearVelocity objects to handle bullets. While this works for slow-moving rockets or grenades, it's a nightmare for fast bullets. You have very little control over exactly when the hit is detected, and you're at the mercy of the physics engine's "stepping."
By writing your own roblox bullet drop script physics using raycasting and math, you get total control. You can pause the bullet, speed it up, change gravity on the fly, or even make bullets ricochet off walls. That level of flexibility is what separates a generic shooter from a polished experience.
Final thoughts on implementation
Building a system like this takes a bit of trial and error. You'll probably spend a few hours wondering why your bullets are flying into the sky or why they're disappearing the moment you fire. But once you get that smooth, arc-based trajectory working, it changes the entire feel of your game.
Start simple: get a single raycast to move forward with gravity. Once that works, add the visuals. Once the visuals look good, move the logic into a module script so you can reuse it for every gun in your game. It's one of those systems that, once finished, you'll never want to go back to basic hitscan again.