Inspired by the Rainbow catch, and Stark's Pump-action Snap, I've build a pump-action Rainbow.
The main grip is very similar to the PAC handles, except for the way it's attached. The handle is screwed in from the top, down into the wood. I had to drill access holes at the top of the pump grip and plunger tube, to get the screwdriver inside the plunger tube.
The white thing joining the back of the gun to the front is a 1 1/4" internal PVC coupler. Here is a link to some sites who sell them. I'm not sure which one was the cheapest. Make sure they are for Sch 40. I cut down the ends of each side to shorten up the gun.
The pump grip pushes back a 3/16" steel rod, going through the plunger rod. There's slotted piece of 1 1/4" off the back of the internal coupler, to align the metal rod. Over all of that, there is a piece of 2" PVC, which floats over the pump grip, and eliminates face-diddle. The 2" PVC also fits perfectly over the 1 1/4" Tee used for the stock. I put two screws through the Tee, and the 2" PVC. Originally I figured I would have to screw the 2" on the other side near the catch. So I cut part of a 1 1/4" coupler, and attached it with set screws in between the gap in the pump grip. I definitely didn't end up needing it since the pump grip fits inside the 2" PVC very nicely. The Tee centers the 2" since it's over the end of the 1 1/4" segment.
The front bushing is a 1 1/4" internal coupler cut off (the left over piece from the other one). Turns out 1/2" couplers fit inside the internal coupler. I solvent welded the two couplers together, and secured it with eight set screws. The pump grip goes over the bushing and past the end of the gun. I cut out section for the hopper clip.
Another random thing. I found a piece of what SoCal nerfers know as "hotrodz", or some random plastic tube that happens to be perfect size (.510 x .625). I was having problems with the spring getting caught inside the catch notch, just before it reached the actual catch. I put a small piece of this tube in there, and it completely stopped it from occuring.
My grand master plan at first was for this to be dry-fire-able, like the PAC. I was going to use this rubber foam tube stuff I got from McMaster which fits in 1 1/4" perfectly. Few problems with it. It added a lot of deadspace. Sometimes the rubber would collapse in on itself when firing. It didn't even pad the plunger enough to make it any less quiet. I even tried using 6-8 inches and jamming it inside. So, for now, my quest for the first dry-fire-able springer is still a dream.
Final thoughts, comments
These things are hella cheap. Sure, I used super nice clear tubes, which were relatively expensive, but you can use opaque stuff. The only piece that needs to be clear (for ease of construction), is the plunger tube itself, which is only about 14-16". The pump grip (2" Polyester) can be substituted for 1.5" thinwall, which does exist. I've seen it at Lowes and it's possible Home Depot may have it as well. It's usually far behind the regular stuff, hidden. So with just the plunger tube being clear, these only cost $15-20.
The only other problem of this is the length. I had 6.5" of draw on this one. I'll definitely cut it down and inch or more, and I can effectively shorten the gun up by a few inches, and it will still be plenty powerful.
Overall, it's beautiful. It has the supa smooth priming motion and re-fire rate of the PACs although you can hide behind trees!
Edited by Ryan201821, 29 October 2010 - 03:46 PM.