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by Solar
Fri Sep 16, 2022 2:34 am
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Re: Valve selection

Piston valves are the best option. When you say you would build one,, what tools are available to you??

I am not sure how to specify piston valves in GGDT.

What is your time line? Use at least a .75" valve.
by Solar
Sat Sep 17, 2022 6:43 am
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Vintage Eclipse Gen1 revolvers etc.

Screenshot_20220917-040943_Chrome~2.jpg
Circa 2008 at Oklahoma D-Day.
Screenshot_20220917-035214_Chrome~2.jpg
by hectmarr
Sat Sep 17, 2022 8:02 pm
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Single-pump handgun

New design and prototype of the single-pump handgun, the "Plink .25". It shoots 6.35 mm steel bb's, because I'm interested in reusing ammunition. There is no point in wasting lead, (more expensive), on this weapon designed for plinking, simply. The pre-compression pressure is 6X and it can go throug...
by hectmarr
Mon Sep 19, 2022 4:10 pm
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Re: Single-pump handgun

Small video that shows the operation of this short weapon.

by getgray
Tue Sep 20, 2022 12:29 am
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Re: Valve selection

Thank you. I have the valve in hand now. It's a beast visually. They don't publish a Cv for it because they said Cv is generally applied to valves with "continous flow" and this one is a pulse so didn't typically apply. Rep has some approximate Cv's which were pretty high, and he's inquired with Jap...
by hectmarr
Mon Sep 19, 2022 7:26 pm
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Re: Single-pump handgun

It is possible to increase the output energy by at least 30%, because it is not very hard to compress, (about 9 - 10 kg), but since the objective is to mark the objective, only that, I have decided that the energy does not exceed that, and not too hard to compress, I mean comfortable to operate. Tha...
by Pennywise
Thu Oct 13, 2022 10:49 am
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Hammer->Qev->Piston rifle

This is my first cannon posting, though i've dabbled in 'spuddery' for many years now. I finally had some time to try a new build design, and I think it turned out pretty well (though i'm still tinkering/redesigning it). 1/2" copper barrel, 3/4" copper cylinder. delrin piston with o-rings, and an eq...
by jackssmirkingrevenge
Sat Mar 18, 2023 8:48 am
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Re: BBMG detent alternative

Something I acquired recently, a "classic" Coksai/Kokusai CAR-15 airsoft rifle: 20230318_092349[1].jpg It works on the "bullet valve" principle that is relevant to the subject of this thread: bulletvalve.gif Some time in the future I'll do a detailed tear down to elucidate the operating system furth...
by jackssmirkingrevenge
Sun Jun 25, 2023 9:49 pm
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Re: Beeman P22 Project

I had given the original P17 in this thread away but acquired a new one and thought I'd give it another go, started with the following modifications: 1) cleaned up the valve stem, installed a harder o-ring and drilled out the transfer port to 3.8mm from 2.5mm 2) added a Delrin sleeve to the chamber ...
by jackssmirkingrevenge
Wed Aug 30, 2023 4:58 am
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Re:

Get SCH 40 2 inch barrel (36 to 48 inches), 2 to 1-1/2 threaded bushing, a 2 inch coupling and some of these for a fun time. Check at your local dollar stores for best prices! Digging this up to say that this was user dewey-1's last post on this forum, ten years ago today. I believe he passed away ...
by jackssmirkingrevenge
Thu Nov 09, 2023 12:26 pm
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Mini Hybrid II

It's been over a decade since I first made this project and almost as long since I dabbled in hybrids so here is a recent project along the same lines: 20231108_233649.jpg Nothing particularly special about the design, chamber volume is around 34cc and it's currently fitted with a 490mm long 6mm bar...
by jackssmirkingrevenge
Thu Nov 16, 2023 1:10 pm
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Re: Mini Hybrid II

I made a 0.177" barrel attachment for this thing, at a 20x mix it was pushing 0.35 gram BBs to just over 1800 feet per second :D that's 39 ft lbs of energy! https://www.youtube.com/watch?v=23-DWhJ0-MA The same barrel hooked up directly to the air cartridge at 2500 psi yielded 1143 fps, still impress...
by jackssmirkingrevenge
Sun Nov 12, 2023 10:23 am
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Compression Ignition Hybrid Testbed

As mentioned earlier what was presented as the Mini Hybrid II is actually a component of a wider project that I will attempt to detail here. I would first of all like to thank hectmarr with whom this project was a collaboration and without whose input would not have happened. Here is an animation sh...
by jackssmirkingrevenge
Thu Dec 07, 2023 12:48 am
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Re: Hybrid disk burst pressure effect on performance

You need something to induce turbulence! Some experimentation was definitely in order, so I machined a Delrin cup to fit the chamber with a 1/4" orifice through the base: 20231206_213324.jpg baffling.png I fired a series of shots and the results were quite interesting. The first thing I did was rep...