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Yet another QEV and 3/2 valve cannon

Posted: Sat Sep 19, 2020 6:09 pm
by Xenophile
Overview of FS resized.jpg
My latest creation. As the title suggests, I using a QEV and 3 position 2 way valve with a 300 psi input from a regulated HPA paintball tank. I have two different barrels, one for 3/8 inch (9.5 mm) steel shot and another for .30 caliber steel shot. The 3/8 inch barrel is currently muzzle loading, but I plan on eventually installing a breach like the one I made for the .30 barrel. The projectiles are held in place with neodymium magnets before firing. The stock is made from some cheap pine that I stained with a polyurethane stain. Eventually I plan on making an integral tubular magazine for the .30 barrel from a "T" fitting.
Ballistics gel test 2.jpg
This is a test using some homemade ballistics gel. I made a 4 Liter block with a standard 10% mix. The 3/8 in shot went in 7 inches and the .30 shot went in 5 inches.

Overall, I'm very happy with this build. I'd love to hear your thoughts!

Re: Yet another QEV and 3/2 valve cannon

Posted: Wed Oct 07, 2020 4:04 pm
by jackssmirkingrevenge
I love the look, and good performance too! Always nice to see people pushing the envelope when it comes to pressure.

Re: Yet another QEV and 3/2 valve cannon

Posted: Thu Oct 15, 2020 5:46 pm
by Xenophile
Thanks JSR, I'm glad you like it!
I've completed a gravity fed magazine ( 10 shot capacity for .30 caliber shot) which is working fairly well, but I am having some issues with double feeding.
Air gun overview .jpg
I'm using a "detent" system with neodymium magnets to keep the shot in place, but this seems to be unreliable. Anyone here know of a good way to construct a magazine (or other device) to minimize double feeds and improve reliability?
Air gun accessories .jpg
I also got another picture showing the completed cannon with all accessories. This gun continues to be an absolute blast to shoot, and gets fairly good gas efficiency. I get around 50 shots from a tank filled to 100 bar (1450.38 psi).

Still to come is a breach for the 9.5mm barrel and maybe a suppressor, although it's only slightly louder than a traditional pellet rifle. Maybe better optics than my hastily crafted laser?

Re: Yet another QEV and 3/2 valve cannon

Posted: Fri Oct 16, 2020 8:44 am
by jackssmirkingrevenge
Xenophile wrote:
Thu Oct 15, 2020 5:46 pm
I'm using a "detent" system with neodymium magnets to keep the shot in place, but this seems to be unreliable. Anyone here know of a good way to construct a magazine (or other device) to minimize double feeds and improve reliability?
One idea would be to have a pressure actuated element that physically blocks the next projectile in the magazine, here are some rough ideas I had sketched:

Image

Image

A spring-loaded detent might also do the trick, it's what my Brazilian Fionda uses and it works quite well, no double feeds.