SpudFiles

HI, i am working toward a semi auto tennis ball launcher. My ideas are a barrel sealing w/ a blow forward loader or a quev w/ a blow forward loader. anyway, i have questions first. And obviously, i am new to "QUEV's"

- Can a QEV be used w/ PVC?

- How easy are QEV's to get? Are they available at ace hardware, lowes or home depot?

-How much are QEV's?

- Isn't a QEV just a pre-made barrel sealing piston?

- Will a QEV do as well as a barrel sealing piston in a semi auto design, espaecially for fire rate?




I'll add that depending on the answes to these questions, new sets of questions will follow.

ok, i read quev's are hard to find. So not doing that any more, so, which would be better for rapid firing rate on semi auto, a modified sprinkler valve or a barrel sealing piston? i guess my question is, Is a barrel sealing piston really worth the extra rouble of making it over a modded sprinkler valve.

i can do rapid fire with mine it just hard cuz if i have air going in when i shot it
then nothing happens so for rapid fire with a piston u must turn off the incoming air then vent the poilet valve
but it is stronger.....
and more fun to make
with the sprinkler valve long as the blogun is closed it refills and u can have air going in it as u fire

so then the sprinkler would be the best thing, especially when i get the blow forward. anyway, can someone give me some guidance as to the construction of a 2.5" blow-forward?

What are you looking for; ease of build, or power.

A sprinkler valve will probably cost you more money, but is easy to modify and will give you a so-so amount of power.

A piston valve (with a spring behind the piston for faster reloads) will cost as much as a couple of pipe fittings at your hardware store and will give you great power. However you must build it nearly from scratch.

JSR had a great thread on a blow forward bolt loading mechanism. Basically you need an outer pipe, a piston that will slide in that, a pipe that fits well in your barrel, a rod that fits well in that pipe, and a spring to push it all back.
Use the search engine to find a better resource on that.

this has been my inspiration, i'm working toward this blow forward.

http://gbcannon.com/pics/GBSemi/gbsemi.gif

i have a question about the blow forward, The pison in it doesn't have to be sealed tight, right?

The better seal the blow-forward piston has, the more efficient the system will be.

i went to home depot and changed back to the piston.