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...

Excellent post!!! You can see all the experimental work with a single glance!!! Thank -you- for this great collaboration :) There is room to investigate different fuels but one thing to take into account when making comparisons is the relative size of the cylinder that is a critical parameter in th...

An interesting question and I thought worth investigating, so I made the following modifications to the Mini Hybrid II : Blunt endcap insert: 20231123_211452.jpg Insert bore tapered: 20231123_214925.jpg I fired two shots each with both endcap variations, for each shot I used a 63cm long 0.177" barre...

Rheinmetall's Fly-K mortar operates on the same spigot mortar principle as much earlier weapons like the PIAT however it marries the idea with the captive piston principle to provide a relatively quiet shot: http://pds15.egloos.com/pds/200906/16/96/c0066396_4a3797df875d5.jpg With some imagination I ...

Something relevant to the original post, an animation I had made of the Russian 2B25 "silent" mortar that works on a principle similar to the Fly-K

This 1400 has languished in my parts bin for some years now, I'm wondering if it could be a candidate for a much more radical project. Here is roughly the concept I have in mind: https://i.imgur.com/farDIxq.gif The "blow open" idea and trigger are preserved, but the chamber and valve are moved in li...

It looks good and I think it's an interesting adaptation. I'm not sure how a sliding breech works... Think of it like the Huben K1 whose magazine feed functions on a similar principle: https://i.imgur.com/ufIaLpr.gif The projectile is placed inline with the valve and the barrel for minimum loss and...

This is very interesting. Intuitively, the highest pressure accumulated before burst would result in the highest velocity. It would stand to reason, though, that you want the disc to burst late enough to raise the chamber pressure sufficiently, but early enough for there to be unburnt fuel mix being...

Am I off my mark? The way I understand it, in a pneumatic the pressure is more or less constant while in a hybrid it's a brief spike. If we have a disk on a chamber that bursts at 1000 psi, then by filling that chamber until the disk bursts there will be 1000 psi of air to push the projectile. With...

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...

pressurepiling.png Looking at this in more detail, the paper describes what is happening in a closed system, with a significant pressure peak happening in the secondary chamber much higher than what occurs in the first one. In our case the dynamic is a little different as we want the second chamber...

I made a second baffle that was both shorter and with a 1/8" orifice that looks something like this to scale: baffling2.png I then did some more testing again at 16x and using photo paper disks and 0.25g airsoft BBs as projectiles: 1) 1 disk no baffle - 1136 fps / 21 J 2) 1 disk baffle - 1851 fps / ...

Any other stand out builds or ideas on here over the last 10years I’ve been absent? My holy grail would still be a large caliber cartridge ejecting semi auto. I should complete that QEV repeater build one day. There's been a lot of small and intricate hybrid builds especially by hectmarr. But ten y...

While using a single o-ring as both a seat seal and a check valve for filling functioned as a concept, I noticed that sometimes while purging the air line it would not reseal immediately, resulting in lower pressure in the cartridge and inconsistent performance, so I've modified the design with a se...

Thank you gents! I love all the effort to keep it looking stock and completely reversable if desiring to use a conventional flare. It also means that the cartridge can be used in any 26.5mm flare gun, I'm really tempted to make a 12 gauge version. I log back into this site every month to see what's ...