geekman9097

Also, you need a metal pin to hold the jam door in place.

Judging by the photos' you might've used it in the gearbox. In my Slingfire, only the lever and jam door use metal pins. The one I mentioned earlier and the one on which the gear stack rests are both orange plastic rods.

The 'Lock' you're referring to is the dart tooth. it goes up front just fore of the magwell, beneath the barrel.

I can't tell from your images, but it looks like the metal bar might be the detent for the lever. there'll be a hole for it just above the lever if it is. it presses against the little plastic extrusion and gives it a bit of a lock to hold it home.

also, if your gearbox is locking up, make sure all the parts sit correctly relative to each other, or find the locks, such as the long orange piece that goes into the trigger void, and remove them.

It's all well and good to model the thing, but how are you planning to manufacture it?

 

Also, as an FYI: I've had good results with 4" of draw in a 1" diameter ID PT (160-180 FPS).

It has about 3" of draw (~80mm)

Once I figure out the missing parts and perhaps refine others it's designed to be a combination of 3d-printing/laser cutting and PVC piping, accompanied by some more basic operations like drilling and cutting.

I've tried to keep manufacture in mind while designing. My only current issue is that I may have used non-standard pipe sizes. quite frequently.