Why Are Paintballs Falling Out Of My Barrel? | Here’s Why

paintball player shrugging with marker in hand
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Back when I first started playing paintball I wanted to be different from my friends so I bought a used pump paintball gun known as the Tippmann SL68-II on eBay. This old beat-up marker was loud, ugly, and paintballs would just roll out of the barrel every time I pointed the marker towards the ground.

While I now know how to stop paintballs from falling out of my barrel, at the time I was just a teenager and simply figured the solution was to never point my barrel downwards after pumping my marker.

So why is it that paintballs just roll out of your barrel?

There are two reasons that paintballs could be falling out of your barrel. The first and most likely reason is that the ball detent in your paintball gun is either broken or missing. The other reason is that the paintballs you’re using are too small for your barrel, but this is only true if you’re shooting a closed bolt paintball gun. 

Below I will discuss both reasons for ball rollout so you can figure out what’s happening to your paintball gun.

Why Are Paintballs Rolling Out Of My Barrel?

If you’re not sure if your ball rollout is the result of a broken or damaged ball detent or from overboring (when the bore of your barrel is bigger than the diameter of your paintballs), then you’ve come to the right place. 

Not only are you going to figure out what’s wrong with your paintball gun, but you’re also going to learn how to fix it.

Let’s begin.

Ball Detent Is Broken or Missing

Ball detents come in many different shapes and forms, but all pretty much do the same thing. On open bolt markers, the ball detent (commonly referred to as a ball latch) holds the paintball in the breach and prevents it from rolling out of the barrel. On closed bolt markers, the ball latch is there to prevent double feeding but does not prevent ball rollout (when you point the barrel downwards and the paintball rolls out). 

Now over time, the ball detent in your marker will slowly break down and eventually lose its ability to hold paintballs in place. When this happens, you’re simply going to have to buy another one and replace it. Fortunately, most ball detents are very reasonable to replace.

Paintballs Are Too Small For Your Barrel

In the rare case that you own a closed-bolt paintball gun, then paintballs may be falling out of your barrel due to overboring (using paintballs that are too small for your barrel). 

To find out if you’re overboring or underboring, simply drop a paintball down your barrel and see if it gets stuck or not on the way down. If it does get stuck, then you’re currently underboring your paintballs. Underboring is when you use a barrel with a bore size slightly smaller than the bore size of your paintballs.

However, if the paintball falls straight to the ground then you’re most likely overboring. Although I would drop a few more paintballs through the barrel just to make sure they all fall straight through. If one falls through and the next one doesn’t then the bore size of your paint may be the same bore size as the barrel.

I guess this would be called boring? 

Different Types of Ball Detents

There are two different types of ball detents — expendable and rebuildable. Both types of ball detents do the same thing, except one is rebuildable and the other is expendable. While the difference between the two can be identified from the name, I’ll go into detail explaining both types of ball detents below. 

Expendable Ball Detents

Expendable ball detents are simply that.. expendable. This means that the ball detent is fairly inexpensive and can easily be replaced. Expendable ball detents are also very likely to break or wear down over time. This is eventually going to happen no matter what if you shoot your paintball gun enough over a long period of time. 

Sometimes your expendable detent may even look perfectly fine but still be worn down. This could lead to the ball detent working on some occasions and on other occasions it could lead to double feeding.

Rebuildable Ball Detents

Rebuildable ball detents are nothing more than ball detents that are not prone to breaking or wearing down over time. For this reason, rebuildable ball detents are likely going to be more expensive than an expendable ball detent. However, since you never have to replace a rebuildable ball detent (unless you lose it), then you may save money over a long period of time. 

Although, in all honesty, in all my years of playing paintball I’ve never had to replace a ball detent more than once, even when expendable.

Open-Bolt vs. Closed-Bolt Paintball Guns

On a paintball gun, the bolt is the main part responsible for firing paintballs at speeds of up to 300+ FPS (Feet Per Second). And while most paintball guns have an open-bolt design, some (mostly older) paintball guns have a closed-bolt design such as autocockers and pump guns. 

The main difference between an open-bolt and a closed-bolt paintball gun is that open-bolt markers have their breach exposed between shots due to the bolt being in the back position. When the bolt is in the forward position and the breech is not exposed between shots then the marker is considered to be closed-bolt.

Another big difference between open-bolt and closed-bolt markers is that the ball detent on an open-bolt marker is responsible for holding a paintball in the breach while on closed-bolt markers the ball detent is actually behind the breach and is only there to prevent double feeding. This is why the ball detent on closed-bolt markers doesn’t prevent paintballs from rolling out of the end of the barrel.


If paintballs are rolling out of the end of your barrel then either your ball detent is broken or missing or you own a closed-bolt paintball gun and the paintballs you’re shooting are too small for your barrel.

To fix the ball detent problem, you either have to buy a new one and replace it or look and see if you misplaced your ball detent somewhere when you were performing maintenance on your marker. If you own a closed-bolt paintball gun such as an autococker or pump gun, then your only two options are either to exchange your barrel with a barrel or barrel kit with a smaller bore (to allow underboring), or to buy bigger sized paintballs.

Another option that will allow you to prevent ball rollout on a closed-bolt paintball gun is to apply a small amount of clear nail polish on the inside of the barrel (on the end that screws into the marker) until paintballs no longer roll out of the barrel. Or if you’re using a pump paintball gun then you can just pump the marker only when you’re ready to fire at someone.
Hopefully, this article has been helpful and you now know how to stop paintballs from rolling out of your marker. Leave a comment below if you’re still in need of some help, maybe I can figure out what’s wrong and provide you some guidance.

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Woodsball player, magfed player, automag owner, paintball sniper. Have played woodsball and scenario paintball (on and off) since 2007 and still loving the game!


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