Are there rules that pertain to the loading process? With the projectile near the muzzle, you could inject a little extra butane (or MAPP) and then push the projectile to its firing position near the chamber. Simple way to make it hybrid I spose.

Thank you!

What should be entered for the settings for valve data in GGDT with a QEV like this one?

How about a dab of super glue on a paper clip?

You can super glue the paper clip to the key inside and pull it out once the glue hardens

Ironically this gun's valve has the best seal out of any other one I've made.

I think I'm just a little demanding with power haha

250psi is the highest my pump will go and most shots are around 220.
When I take the gun apart I'll take a picture of the piston and weigh it. It's solid delrin, about 1.5" long and 1.2" in diameter.
The piston travels about 0.3"-0.5".
I'm thinking the power issue comes from the small chamber.

I ...

The piston has a great seal, but I kinda like the power behind a one-shot system, despite it being a long process to fire.

I was thinking of carrying around a paintball tank and having a regulator supply the gun with air, which will remove all the time spent filling it with a bike pump.

I haven't ...

At 250psi this sends a 12.5 gram lead ball at ~490fps



The index finger goes into the loop



The steel pipe chamber makes this gun heavy. I'm considering replacing it with a copper chamber.

You got the stock right. I have a picatinny rail but I decided against mounting it since the tape is good enough for me. I'm doing any shooting past 50yds.

I'll post some pics of the other gun. It's actually piloted by a quick disconnect

It's a fairly light gun, compared to the barrel sealer I have (in the background of the second pic). It's not as powerful though, so it's just for backyard plinking.
Lead balls fly a little too slowly with this gun for my liking, so I'm also looking for some lighter ammo that I could use, and maybe ...

^Nice video

I redid the shot with the muzzle 3 feet from the chrono's first sensor and hit 1102 fps.

Learned my lesson here.

Based on this shot and another with a lead ball, my flow coefficient is somewhere between 30-50%. What are other people using in GGDT for the flow coefficient of their ...

Thanks for the tip.

I'll be redoing this shot in a few days, and I'll also dry fire the gun through the chrono to see if muzzle blast alone can create a reading. Is water vapor really dense enough to trip the chrono's eyes?

Yeah I thought about it some more after I commented and figured the numbers were a little too crazy, so I posted here. I'll definitely redo the shot from a few feet

Is there something I'm doing wrong here or did the chrono somehow misread the shot?

Everything I entered in the GGDT matches up fairly well with the conditions I had, and everything was measured with digital calipers and a digital scale. I couldn't figure out the exact chamber volume or pilot ...

This is so untrue; you can definitely send a projectile off faster than the speed of sound of the gas you are using.

It really just depends on how much energy you put into the gas and how well you can use that energy.

If I made a burst disk cannon with the disk's rupture pressure around 10,000 ...