This is my second air gun. I call her Good ol' Boomer. She can blast through nearly two 2x4s using lead and steel balls and will embed the same ammo deeply into a 4x4! According to GDDT I'm getting around 650-700 fps with 177 grain lead balls at full power, I'm a little skeptical of that though...
Specs:
Valve: 3/4" QEV piloted by a 1/2" QEV, this is then piloted by a 1/4" ball valve.
Barrel: 1/2" type M copper, 60" Long
Chamber: 3/4" steel pipe, 30" long
Operating pressure: 100 - 400 psi. Can go up to 600 but too scared.
Shooting at a water bottle with a marble
Shooting a 1/2" steel ball through a wheelbarrow, the table behind it and 1" pine. Shot at 60 paces.
Hope you like the gun/damage pics. Any suggestions on improving ergonomics/reducing pilot volume would be welcomed!
Good ol' Boomer - damage pics and videos
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- Full gun
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- Close up of valve assembly
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- 2x4
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- An old kettle
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- The 4x4
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- That's 3 inches deep!
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- This little bugger passed through over 800 pgs of magazine! As a comparison, my .22 springer will struggle to make it through 100.
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- Lead ball vs can filled with water
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- Some more shots at the kettle.
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Ianbuckwell
- Specialist
- Posts: 157
- Joined: Tue Apr 01, 2014 1:13 pm
I haven't watched all the videos as on my phone, but that is awesome power, what brand are the QEVs? And do you have to mo them with spring/pin hole?
Very nice indeed! That looks very powerful to me. If the QEVs are the cheapies from ebay, how did you get them to work properly after modifying for chamber feed? I couldn't get this type to work but the black box QEVs work fine for me.
For reducing pilot volume, I saw that someone stacked rubber or plastic washers in their pilot chamber,still allowing for airflow but reducing air volume.
As for the ergonomics, I'd carve a nice hunting rifle stock for it and put a bipod under there because it looks heavy!
Cheers
For reducing pilot volume, I saw that someone stacked rubber or plastic washers in their pilot chamber,still allowing for airflow but reducing air volume.
As for the ergonomics, I'd carve a nice hunting rifle stock for it and put a bipod under there because it looks heavy!
Cheers
@ Ianbuckwell - Thanks for the comment. The QEVs are from Alpha Technologies, ordered from Fastenal. They perform well and no sign of wear on the Pistons after 50+ high pressure shots. I think the cv for the 1/2" is 5 and the 3/4" is maybe 5.5. Nope, no modification required.
@ Doodmens - I fill from the pilot, not the chamber. That's a great idea, thanks. I have lots of washers lying around so I'll have to try that! If I don't open the BV adequately the piston vibrates in the QEV so I definitely need to reduce the pilot volume. It looks cool in slow motion though :p. As for ergonomics, that would look nice, but the gun is over 5ft long so I think a bullpup confit would be less ridiculous xD.
@ Doodmens - I fill from the pilot, not the chamber. That's a great idea, thanks. I have lots of washers lying around so I'll have to try that! If I don't open the BV adequately the piston vibrates in the QEV so I definitely need to reduce the pilot volume. It looks cool in slow motion though :p. As for ergonomics, that would look nice, but the gun is over 5ft long so I think a bullpup confit would be less ridiculous xD.
I have to admit that I'm surprised. Boomer isn't that different to the way I've got HEAL set up - a 20mm piston valve piloted by a 1/2" QEV, connected by about 40cm of 8mm tubing to a 1/4" sleeve valve; all the valve flows, pilot volumes and the like are broadly similar. Even the same "S-kink" chamber - the only significant difference I can see with respect to their mechanics is the exact sizes of chamber and barrel*.n05gr0th wrote:If I don't open the BV adequately the piston vibrates in the QEV so I definitely need to reduce the pilot volume.
Still, I've never had "honking" problems with HEAL. Which of the valves is doing it? The 1/2" pilot?
*In that respect, I can definitely empathise with you about taking a bullpup approach! At one point HEAL had a 125cm (~49") barrel, but even that I eventually decided to cut it back to the 100cm (~39") on my original blueprints just to keep the lengths more practical.
Although, that said, I'm guessing Boomer has more like 6-7" behind the breech? HEAL's valve assembly is almost deliberately long at closer to 10", and it does obviously all add up.
Does that thing kinda look like a big cat to you?
@ Ragnarok - it's no coincidence. Your cannon along with Dave_224's 600 psi launcher were my main inspirations!
I believe it's the 1/2", I can only avoid honking if I pull on the BV extremely quickly and fully so it must struggle to dump the pilot volume fast enough... I'm considering just spring-loading it so as to avoid fiddling with the fittings too much (they were a b*tch to seal). Do you think reducing the pilot volume between the 1/2" and 3/4" QEVs would get better results instead?
Here's a video of a failed shot, it doesn't sound like honking though:
Haha I was in a similar position when designing GOB. I almost went for a 72" barrel!
Close - I measured it a while ago and it was something like 5".
Missed a few shots today...
I believe it's the 1/2", I can only avoid honking if I pull on the BV extremely quickly and fully so it must struggle to dump the pilot volume fast enough... I'm considering just spring-loading it so as to avoid fiddling with the fittings too much (they were a b*tch to seal). Do you think reducing the pilot volume between the 1/2" and 3/4" QEVs would get better results instead?
Here's a video of a failed shot, it doesn't sound like honking though:
Haha I was in a similar position when designing GOB. I almost went for a 72" barrel!
Close - I measured it a while ago and it was something like 5".
Missed a few shots today...
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