Converting Paintball Marker to Airsoft SMG




What follows hopes to be a simple, cheap and effective way of converting any Paintball marker to fire BB's at high velocity. Beware that this is in no way safe to use on the field unless well tested and adjusted on a chronograph to avoid injury.

Disclaimer: I will not be held responsible for your actions and any injuries that result from the making or usage of this device.

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Step 1: What You'll Need

Basically you need to start by gathering the following tools and resources

Step 2: Start Making

Drill a 7mm hole into the side of the barrel about 3 to 4 cm/1 to 1.5 inches from the thread (Make sure that the hole will be on the top or slightly to the side of top when the barrel is screwed in), this is where the BB feed will eventually enter your barrel. U should know that this device uses a BB barrel inside a PB barrel.(Please read the entire Instructable thoroughly before drilling)

Step 3: Making the Bullet Control Point

Drill 4 holes into the wooden dowel to create something like the pics.

The dowel is cut to about 3cm/1 inch long.

Step 4: Putting It All Together

Slide the BB barrel into the corresponding hole in the control unit and epoxy it in place.

Slide the Control Unit into the PB barrel until the two feed-holes Line up and epoxy into place (the epoxy is to prevent the "Unit" from becoming a bullet while shooting.

Stuff the space between the Barrels with tissue or newspaper (or preferably Epoxy or Bondo, but I didn't have that much to waste), Get the BB barrel centered as good as possible, as this is going to define the accuracy U get from the device.

Slide a short (5cm/2Inches max) portion of the barrel onto the feed holes, not to deep (there should still be enough space for the BBs to move from The feed portion into the main barrel)

Step 5: Finishing Up

Drill a 7mm hole in the bottom of the Pill bottle where it will fit over the feed portion and feed BBs into the system.

Step 6: How to Use

This System works on the principle of the Venturi effect whereby the BBs are sucked out along with the outgoing air.

Screw the barrel into the system
Plug The Marker hopper port to get the most power
Fill the 'hopper' with BBs
Pressurize your marker
Have Fun!!


Step 7: Additional Notes

Start with your marker at minimum power, this is for safety reasons as well as for structural integrity testing, the system might not be able to handle full pressure.

This is a very powerful device and can rip soft drink cans to shreds even at minimum pressure.

Add laser sights or flashlight to the barrel, A scope is unnecessary as i find it is more of a SPRAY AND PRAY system. 

I can shoot 10cm/3 inch targets at  15 meters/ 45-50 feet so it is fairly accurate.

leave me a PM or comment on ways the improve the device or instructable, or even if you have questions.


Accuracy: 6/10
ROF: 9/10

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    10 Discussions


    2 years ago

    can you buy the converting barrel ready made?


    8 years ago on Step 7

    you could pull the bb barrel all the way to the place were the pb ammo feeds in so you don't have to plug it up or drill a hole into the pb barrel


    8 years ago on Introduction

    me and my friend are trying to mod his old tippman 98 into a airsoft sniper rifle. this will help loads.

    2 replies
    Billy mahonyilpug

    Reply 8 years ago on Introduction

    let me know if you would like to see some of the improvements i've made to this initial design, mine is now magazine fed and much more reliable.


    9 years ago on Introduction

    oo this looks like it would really hurt!......I have to try it!

    Billy mahony

    9 years ago on Introduction

    I have just realized a major flaw in the design, the feed-barrel is still a barrel, it fire bullets up into my hopper. Luckily I have plans for a more intricate magazine fed design. Leave a comment if you would like an updated instructable.

    Billy mahonyCaseyCase

    Reply 9 years ago on Introduction

    yeah, i just checked that out, More user friendly (because you can adjust the pressure), But mine has to be a very good alternative


    9 years ago on Introduction

    Hey, my girlfriend' dad did this with an cheap stryker paintball gun. He was shooting 4.4mm stenlesssteal BB, and the accuracy was really good. Could pop a balloon at 100feet.