This is a work in progress but my help stimulate some thinking about how to build an autoloader.
So anybody that wants what I have so far including how to Word files can ask via e mail firstname.lastname@example.org
First, it is a screw-on UPGRADE for any cannon or RPG. It goes right on the outlet of the main valve. Self contained and has only two moving parts unless you count the three springs moving. An amazingly simple design that I didn't believe would work because there are so many guys that are smarter than I am building stuff. Surely someone had to try this before me. I had to build one to find out why it did wouldn't work but it worked!
PVC, Wood, hardware store hardware, springs, etc.
Cost very little to build using basic shop equipment for Wood and Plastic fabrication. I believe in the KIS principal and many of my upgrades are just easier and more simpler ways to fabricate it or make it lighter and more compact.
The 6 shot autoloader as seen below the 4 shot magazine adds only 6 pounds to a standard RPG or cannon. My Shorty RPG weighs 6 pounds minus the HPA supply so a homemade, autoloading upgrade should come in around 12 pounds. I continue to work on upgrades. I have sucessfully tested a barrel that drops 2 pounds off the standard schedule 40 PVC barrel that is 24" long. Yes, it weighs near NOTHING!
How it works with illustrated pictures:
Indexing and moving the magazine is where everyone gets stuck... So more detail:
My 6 shot magazine below where I tried an indexing SCREW instead of the lugs. It worked but I'm not satisfied with the BEST way to index yet in terms of ease of fabrication. It was very difficult to instal.
You can SEE the fabrication of the 6 shot mag was MUCH simpler than the fabrication of the 4 shot mag. Experimented with a wide variety of fabrication materials and techniques. That piston is LITERALLY pounding on that magazine and its construction has to be quite robust to survive that. About 100 pounds of force with each shot. My testing included putting a piece of plywood over the back of it and beathing it to death with a big rubber mallet. Stood on it (220 lbs) and threw it down the stairs repeatedly. Found several technique that would hold and many that would fail. Just e mail me for the pics and materials of what worked.
Glued three PAIRS together first.
You can see where I tried to glue the indexing lug in the seam. Eliminated that fearing the lug would hang up on the piston as it rotates IF the piston doesn't retract quickly enough. I don't know it won't work. NEXT upgrade, I plan to try it. Just extend that carbon fiber arrow shaft about 1/4 inch over the edge. If it DOESN'T work, just cut it off, file it flush, and use the indexing screw again. Worth a try for that amount of extra time. Pondering if I could put a 45 degree chafer on the outside of the piston and one side of the carbon fiber to reduce the likelyhood of the piston hanging up. Use a heavier retraction spring on the piston. Smaller diameter of the outlet through the piston into the chamber would take a bit LONGER for the pressure to drop to zero giving the retraction spring a little more TIME to get out of the way... Lots of Tweaks to tinker with to maybe get it to work reliably IF it is a problem in the first place...
Then assembled and glued the three pair to make the 6 shot mag.
A combination of SuperGlue, epoxy, fiberglass reinforcing POWDER and Fabric plus carbon fiber arrow shafts turned out to be pretty much bullet proof and easy to fabricate. The super glue is used primarily for the initial set up to hold it together temporarily just to make it easy to handle while you apply the carbon fiber, epoxy and reinforcing fiberglass powder and fabric.
You can see what I made that barrel out of below. Working on fabrication techniques to make a magazine out of the same stuff. See the black carbon fiber shafts used to reinforce the glue joints.
Anybody want to play with my "Invisible RPG"? Very early in the R&D but the material is a 2" x 24" polycarbonate mailing tube. It shot 230+ fps Nerfs out of my Shorty RPG operating at 145 psi. Makes a lovely ultralight barrel you wouldn't want to fall on top of. It would break. BUT is slides INSIDE schedule 40 and could be used as a LINER for a PVC barrel drilled full of holes to lighten it. It would look cool too... Line an MEGA 50 cal barrel.
Question? here or e mail.
Now you don't have to carry the whole thing in your hands. You can put most of the cannon hardware and HPA on our back. Does this pic give you any ideas for a screw on upgrade for an autoloading RPG?