I don't think that it's particularly wise to recreate this, as it is rather complicated, and very picky about the darts you put in it --malformed taggers can get stuck in the magazine, causing misfires. Also, if the plunger is held down for long after firing, an extra dart can fall into the breech area, and cause a jam. There is no reason to hold the plunger down after firing, but for some reason it's my natural instinct. Both of these problems are usually solved simply by firing the gun a few times, but it's still far from a reliable weapon. I understand that it's cool to have a semi-auto nerf gun that shoots taggers. I also think that it's probably the best combination of range and ROF available for tagger darts, but that's kind of like being the coolest kid on the short bus. Anyways, here are the basics of how it works and how it's put together
The HAMP motion is used to open the breech, and is mechanically linked by PEX tubes inside PVC tubes. A rubber band returns the breech to the closed position. This requires a low friction seal between the magazine and barrel breeches, and the breech covers. I know of no readily available material that does this on EMT as shown here--These were made from some Walgreens blowgun toys I bought a few years ago on a roadtrip. Rarely, thinwall PVC will be loose enough to slide freely. A steel pin connects the bottom (barrel) breech cover to the PEX tube, and the top (magazine) breech is simply taped to the bottom breech.
In order to get a dart above the breech in the magazine, all of the darts in the magazine are sucked back by pulling out the plunger. In order to prevent the darts from being blown out of the magazine by pushing in the plunger, a fairly high airflow one way (check) valve is used. It was salvaged from an REI marshmallow gun, but I know know how to make a high airflow check valve with a PVC connectors, and some cut up rubber sheet. In order to prevent the air from being sucked in through the barrel (which would prevent the magazine from functioning), the next dart in the chamber seals the barrel fairly well, and is held from being sucked further back by the breech cover pin. This DOES mean that the magazine has trouble loading the next dart, when there is no dart in the chamber, so one misfire usually leads to a few more before a dart drops in.
The barrels are EMT steel tubing, the clear dart-retention cover is from a plastic spinach box, and the rest is PVC connectors, duct tape, and a HAMP, which you can find here:
And here's a couple more pics showing the breech and plunger, in open and closed positions:
Open breech, plunger in:
Closed breech, plunger out:
Edited by KaneTheMediocre, 01 March 2010 - 08:10 AM.