SpudFiles

what do you mean?

Naturally the QEV will open faster and give better flow so you can expect a considerable increase in power over using a blowgun, plus depending on how you pilot it a QEV would be more consistent.

sounds like a qev for me, i thought a blow gun could be a good option becasue for a bb/pellet you don't need a super high flow.

you don't need a super high flow.

...but you do need fast opening time to "shock" the projectile with as much pressure as possible. Also, for small calibres, pressure is more important than volume. A small high pressure chamber is a much better idea than a large low pressure one. Commercial airguns use tiny amounts of air per shot, but at pressures over 4,000 psi.

cool, so if i used a 20cm 3/4" chamber and an 80cm 6mm id barrel (2.5:1 ratio) with a .22 bb a 1/2" qev piloted by a 1/4" blowgun at 150psi what speed would i be looking at getting?

GGDT it, unless you're asking someone to build it for you and check the velocity. BTW there are no .22 bbs, there are round balls and pellets, the latter being more common. Assuming a common 14-grain pellet, I'd say 400-500 fps, but that's just my guess.

i thought you could get .22 gram bbs? and i don't have ggdt so i was hoping someone would put it through for me HINT HINT.

windshrike wrote:Assuming a common 14-grain pellet, I'd say 400-500 fps, but that's just my guess.

A quick GGDT model suggests 500-600 feet per second, but again, the low pressure is your limiting factor here - buy a shock pump

i thought you could get .22 gram bbs? and i don't have ggdt so i was hoping someone would put it through for me HINT HINT.

You can get 0.22 lead balls but not 0.22 steel BBs, though I believe there are aluminium and steel bearings available in 6mm.

Nope, round balls only, unless you just get .22 ball bearings from someplace(ball bearings are not bbs just so you know).
Pellets are cheap and self-stabilizing, even in a smoothbore barrel so I'd go with them. I got the hint, but I'm on my laptop which has Vista so I can't run GGDT unless I boot up the old desk machine(which takes forever, 256 MB of RAM doesn't cut it). Is 150 psi the limit because of your QEV? With a project like this I'd try to get one that is higher rated to take the gun up to AT LEAST 200 psi.


EDIT: Well, while I typed this up, JSR put in a GGDT reading, so there ya go.

thanks for the ggdt but i was hoping for more power. the qev is the limiting factor, maybe i will try a homemade piston.

Thanks Guys that cleared things up for me. I bought me a brake line today for my rifle. I will be useing a 22 caliber pellet for my rifle and a 177 caliber for my pistol. I was wondering what time frame are we on. I work nights and don't get to do much work on it. Yall decide if we don't put a deadline we will never finish. What say ya. Thanks Chuck

ALIHISGREAT wrote:thanks for the ggdt but i was hoping for more power. the qev is the limiting factor, maybe i will try a homemade piston.

A QEV is essentially a piston or diaphragm valve, and I'm sure it will happily take more than 150 psi.

well its rated to 150psi and i can't find a higher rated one so i might try a berrel sealing piston.

Well Guys how are yall coming along. Got two rifles made in the rough. One a 177 caliber rifle the other a 22 caliber rifle. I took pictures tonight will post tomorrow. I am using ball valves and sprinkler valves. Will build one later on out of a Qev. Thanks Chuck

sounds good, and about the time frame, i'm still planning my cannon so it could take a while to make.