Forums | Death by Foam | Articles | Modification | Homemade | Links | Store | Gallery | FAQ


Nerf Expand-A-Blast

Nerf Expand-a-Blast


Expand-A-Blast SCH80 barrel and spring replacement mod:

This gun sucks. Look at it. When you fold down the front handle the barrel and stock pop out and supposedly enhance it in some way. Out of the box it barely shoots 20'.The first thing I did was open it up and remove all the stuff that makes the stock and barrel pop out. Next I picked out a nice replacement barrel for it. That oversized plunger tube generates a very fast airflow for a spring gun but as a result it doesn't have much force behind it. I decided to go with SCH 80 PVC since the 17/32" ID offers a slightly loose fit with micro stefans.

Here's the plunger assembly with the 11.5" SCH 80 barrel. The purple thing on the end is the pump end cap from my SM5k. Anything will work here - it's just to bridge part of the gap between the PVC and the orange tube. You want it to be totally airtight and epoxy won't bridge a 1/4" gap very well. The blue thing is a scrap from an old mousepad I had lying around. I rolled it around the barrel to keep it centered in the tube.

24 hours later, it's perfectly airtight.

Next I removed the spring and replaced it with something a little stronger. The new one is in place and the old one is below it for comparison. I got the spring at OSH - it was originally twice this long but I cut it in half so it would work here.


The ammo holder is made from scraps of SCH 80 hot glued in a ring so that it slides over the barrel. Using the ammo holder I can get off 7 shots in about 15 seconds. Not a bad ROF for a gun with this range and accuracy.


I range tested it with micro stefans, angled and flat, 5 shots each, averaged, no banding.

Average Flat Distance: 74', 8"

Average Angled Distance: 100', 5"




All images and content © Kevin Davis 2001, 2002 - Hail Eris! All hail Discordia!