I have been using the chart posted in the forum, I haven't done any calculations.

For 10x 6.44 ~6.5 psi propane
138.74 ~ 140psi air

Are you saying I need to subtract 15 psi?

So 6.5 and 125?

I'm thinking about giving the volumetric route a try. I cant get any real consistency right now. Makes a nice bang when it does go off though.
I dont have any real way to measure the volume at the moment. So for now I'm messing with the pressures. Not sure which gauge is wrong..

Eventually ill figure out how to quote, and use the forum properly, but for now... I use a 4500 psi PCP pump for air. It has to be a mixing problem, I personally attributed the small chamber as why it doesn't mix well. My thought is it only takes maybe 5 pumps to reach 150 psi so not much mixing act...

If you find some with the right size head, you dont need to remove it and it will apply some drag stability. I like the nails for hanging pictures.

I have made a few pen guns, always thought shooting small nails was fun. Or "skewers" work as well.

Unfortunately I did not. I know you guys want videos! I am here in Colorado and we have snow at the moment... we should have some nice weather coming up. Maybe this weekend... I have switched over to my hybrid though. As far as I am concerned this thing is complete, a smashing success. I even replac...

So the gun has a piston valve. If you have seen my other rifle, this is a clone. The only difference being a venting pilot valve, a spark plug, and the piston does NOT have a check valve. Because of the identical construction I can use the rifled barrel on both of my projects. My miss fire issue is ...

Since posting i believe i have figured out my issues. I noticed that if I leave the gun sit for roughly a minute before firing it goes off reliably. I increased the chamber volume aswell.

I am in the process of creating a "venturi" fuel mixing system to mix the gasses as the chamber is filled.

So a little update, I did a little shooting. At 1000psi I got 586 fps. Roughly 275ft/lbs. At 3000 I launched the chronograph across my drive way and I to several pieces... so not real performance data. How ever in the never ending quest of moar-power I have assembled a hybrid out of nearly identical...

So I've put something together, its a hybrid clone of my phenumatic rifle. Right now they share a barrel but it will get its own dedicated when complete. For the time being I have had a few successful test shots at 10x using the chart from the forum. They are hard to repeat. But I have had some succ...

Unfortunately these things are so small it would be very difficult not to shoot the chronograph itself or miss entirely at those distances. But I do believe it is directed at airsoft and other low power toys so I'm not complaining. We will see what happens this weekend. I am going to try to get up s...

I would assume they are manufactured to the same standard as automotive spark plugs. Could always rig something up and do a hydrostatic test. But these are kinda pricy for a destructive test. I did find some alternate brands that are a little cheaper.

Hey guys just came across an interesting product while looking for spark plugs for a hybrid.

These come with a standard pipe thread with multiple options for length. Check it out.

http://bgservice.com/auburn-igniters.html

I got off a little early today. I decided to play with the chrony a little bit to see if I experience the same as JSR. I recently picked up a "beeman comander .22" its a incredibly priced PCP rifle. I ran a string of 10 shots (only one power level) Every shot was between 274 and 279 M/S came out to ...

Mr. JSR talked me into picking up one of these things. $28 delivered. It did not realize how small it is, this thing is tiny. I hope the muzzle blast doesn't destroy it. . Fingers crossed, this weekend i will do some more shooting. Cant wait to see some numbers.