Finned projectile 37mm
Federal Labs Inc
Here's a photo I found on the web of an old federal finned projectile. Just looking at it starts my brain to working... (or smoking) The design is apparent, so I'll just post the photo, and you guys that were trying to make a finned projo can get some ideas from them. Good luck, and let me know how things turn out!
It's a rather long projo, but the payload section could be shortened to fit smaller launchers. I love the design, but don't have the time to do research on it myself. GROG