The gun uses a very powerful spring, which makes for an extremely fast air delivery system. To prime the gun, much like in the Pistol Splat, it needs a mechanical advantage system. For this it uses a reducing gear ratio. The pump arm moves a solid 4 7/8", while the plunger tube and plunger move a meager 1.5" when the safety spring is installed, and a half inch more when it's removed.
The objectives for this mod were:
Keep the pump action system
Add a linked brass breech system to improve rate of fire
Keep the break action
Allow for shotgun loading
Convert the inline clip to hold darts
Starting off, here's a picture of the inside. Nothing really shoots out too fast when you open it, but there is potential for it to happen.
You can see the gears that rotate on two posts, are turned by the rack attached to the pump shotgun handle, and the teeth on the plunger tube.
Important: The piece above the plunger tube clicks down when the plunger tube is moved forward, and the gun is primed. It stops the plunger tube from moving backwards again, and stops you from priming the gun again. Remove it and its spring completely. This will allow us to open the breech later more than once, so that we can shotgun load.
Here is the front half of the gun kind of broken down. You can see the inline clip. Slug covered how the gun functions normally in his writeup, so I'll skip over those details. It's very interesting though.
Here are our plunger tube and plunger. That beastly little spring is to decelerate the plunger at the very end of the stroke as a safety mechanism. Go ahead and remove it.
To take the top half of the front half of the gun off, take out the screws in the back and the one at the front, and push it off. You'll have to rotate the handle 180 degrees, after unscrewing it from the rack, to slide it off.
Getting to the modding, hammer a fine nail through the end of your plunger tube, about 1/4" from the outside end of the tube. Make it as parallel to the tube and as centered as you can get. Then take out the nail and use pipe cutters to cut the tip back to about 1/2", again, from the outside end of the tube.
Dremel back all four quarters of the shell to accommodate easy movement of the plunger tube with the nail. Here, only the back two are shown.
After cleaning out the hole in the plunger tube, use a piece of 9/32" brass, and mark the distance from the nail to the tip on it.
This part is our major breech piece. Made from 5/8" brass, it has a half pipe cut starting at 1.5" from the left that continues for 1.5". It's 6" total in length.
What you need to do is mark at what two points the brass would hit the nail when the breech would be point up, then turn the brass slightly, and mark the two intersection points again. Now mark the distance that the nail is from the plunger tube onto the brass, between your marks, and you should be able to cut a shape like the one in the picture into the tube.
This should allow, and you need to double check that it does, you to slide the brass down over the nail, then turn it to lock it in place. This is how we're going to keep the break action with the linked breech.
Cut the piece of 9/32" back to 2" from the end of the mark. If anything, cut this piece too large.
Spray silicone based lube onto the brass and outside front of the plunger tube. Now quickly wipe it off of the brass. Put the brass piece into the plunger tube, like so, and put enough hot glue so that it doesn't overflow more than the 5/8" brass would be able to handle, but seals nicely to both the tube and brass.
Before it cools, the long uncut end of the breech piece onto it's nail lock, unlubed. Hold the tiny brass piece as parallel as you can.
After that cools, take off the 5/8" piece, and gently pull the 9/32" piece out of it.
Find some more 5/8" brass and lube up one end. Put a ring of hot glue onto the piece of 9/32" near the end that's not marked. The brass can't be lubricated. Spin it as it cools, and then when you can, add another ring. Repeat until it's slightly bigger than the piece of 5/8" brass.
For this next part, you'll need a 1/4" piece of brass, and something that slides over it and can push on your piece of 9/32". I used a scrap of bic pen.
Edited by Splitlip, 20 March 2009 - 12:08 AM.