Today I will be doing a write-up to build your very own Buzz Bee Big Blast with an integrated Airtech 2000, with a shared stock pump. The point of this project is to install a secondary air chamber into the internals of this toy, so that some of the air from the main pump is redirected to the smaller tank. One reason for this is so that their is a lower air pressure in the large air tank, meaning the foam darts hurt less if shot out of that tank’s barrel. Also, the secondary air chamber means a nerf player has a backup shot ready at any point, for situations where they are caught reloading the primary barrel.
- 3/4″ to 1/2″ PVC slip fitting
- 1/2” PVC coupler
- Polycarbonate in varying sizes
- Various hardware
- Goop, Gorilla glue, and Solvent weld
- Polyester Resin – optional but recommended
- Vinyl tubing- 1/4” OD 1/8” ID
- Super Soaker Shot Blast pump., or any check valve that will fit
- Brass tubing connectors
Step 1. Get your Big Blast
Remove the Orange Ring
And open it up
Step 2. Find the section of plastic on the side of the tank (See pic)
And remove it
And then remove the stock barrel
Step 3. Get a 3/4″ to 1/2″ PVC slip fitting
And then sand the 3/4” side till it fits the end of the tank
Apply solvent weld to the tank and bushing and let it dry, be sure to do so in a well ventilated location, preferably outside
Step 4. Find the middle wall where the tank/barrel goes (see pic)
And trim it down, repeat for the other side of the shell
Make sure your tank fits in place nicely
Step 5. Now minimize the shell
Then you will need to widen out the hole for your PVC barrel.
You could stop here and have a great simple and clean primary
But part 2 of this mod is integrating an Airtech 2000 tank
Part 2, step 1. Get a 2k tank, and glue it to a pvc coupler that is cut down so it rests snuggly in the tank
Line up where you want the tank’s coupler to be on the gun
And cut a hole for the PVC barrel
Step 2. Next you will need to machine a trigger
Then line up where the pin would go in this trigger. and cut it to fit- also cut a notch in the shell for the trigger pin
Step 2 Continued. Then you will need to screw a side-plate on both sides of the triggerStep 3. To hold the tank in place, I poured a Polyester resin into the shell, making sure to cover the tank to protect it. You can get this resin at a local craft store, I will explain it further in a future topic
If you have any resin left over, go ahead and reinforce the shell
Now all that’s left is to link the air lines!
Step 4:The pickup line for the 2k needs to be close to the base of the pump tube, to
receive a full “stroke” of air each pump.
That’s where you’ll drill the hole for 1/4″ OD tubing. Clean up any debris that might find its way into the pump tube. Crumbs of plastic will destroy your pump’s oring quickly.
I followed my usual routine of tacking the tubing in place with super glue(I
use Gorilla brand exclusively), then following-up with some Oatey’s red can
PVC/CPVC/ABS cement. Goop could be an alternative sealing method, but I hate
the long cure time and the solvent in PVC cement will “weld” the tubing in
While that assembly cures, use the same process to attach tubing to the 2k tank. Add a narrow diameter spring to the tubing here, to prevent pinching of the line when bent. Pinched lines won’t allow air into the tank efficiently.
Here’s the check valve in place on the line from the pump tube. The check valve is necessary to prevent both tanks from emptying each time you fire one. In this particular case, the 4B has a check valve in the base of the pump tube, so we only need to add one to the 2k’s input line. Obviously you want the valve’s flow oriented into the tank.
A little creative routing gets the tubing from the 2k tank to the rear of the shell. Drill a hole through the bulkheads, larger than the tubing to allow movement. Debur the holes to prevent unnecessary chafing. Be sure that no lines are pinched, and that no lines impede movement of the trigger assembly.
And finally, all linked up.
This setup is efficient, but doesn’t provide “lethal” pressures to the 2k tank; so it’s a great backup or “mercy” shot rather than launching a full-bore 4B shot to someone point blank.