hybrid cartridge protoype without burst disk

[Crna Legija]

good old Sam Kekovich, i love all of his adds and the new VB add

[jackssmirkingrevenge]

Well if you think of it you might as well build a larger cartridge for 3/8" bbs... Who said it has to fit a pistol?

I could make a cartridge the size of a magnum pistol round that could fit into a launcher the size of a Desert Eagle, but I think I'm more inclined to make a "short long gun" as already mentioned, such as the sawn-off M1 from Hellsing or Clyde Barrow's BAR

Maybe it wouldn't be a bad idea to build a break barrel gun similar to the M79. That would have both the coolness factor you're after and should be relatively simple to build

Nah mate, the spent cartridge doesn't fly out

A direct blowback mechanism along these lines really shouldn't be that complicated to put together, it's getting the cartridges to work as planned that's the trickiest part

To do anything else would be Un-Australian!

You know it makes sense

[POLAND_SPUD]

Nah mate, the spent cartridge doesn't fly out

yeah I know, but it makes a cool sound when you insert the cartridge
well what about this -> http://world.guns.ru/grenade/gl16-e.htm
still it does not exact cartridges, but it doesn't change the fact that it is pretty cool

[Crna Legija]

what about the AA-12 you could have bigger shells that still fly out

[jackssmirkingrevenge]

After some consideration, I decided I would probably like to have something that will fit in a Desert Eagle sized package or something a bit more imaginative, so I decided to make an even smaller cartridge than my micro prototype, of course power would suffer but as long as it blows back it's fine by me

In that regard here's the latest prototype with 9mm and 7.62mm rounds for scale, o-ring seal seems to be holding up well but the epoxy isn't cured enough for ignition testing, watch this space.

[ilovefire]

yay another of your creations
what is the width and height? and what is the chamber volume?

[jackssmirkingrevenge]

You can bet it won't be the last

Overall length including schrader is 1.5 inches, I/D is 0.55 inches and volume is around 3mL

[ilovefire]

You can bet it won't be the last

sure hope not!

Overall length including schrader is 1.5 inches, I/D is 0.55 inches and volume is around 3mL

3ml is the same as my mini bust disk (kinda broken though) i think i got it to fire at 6x and with a 40cm barrel went i think just bellow the surface of a pine board with a steel bb, but i know i wasn't that impressed with it so maybe at 15x (20x if possible) it shouldn't be to bad though

[jackssmirkingrevenge]

Hmmm... looks like I'm going to have to combine the o-ring with the seal for it to work out.

[ilovefire]

let me guess it looses to much gas before it seals? had the same problem when i attempted something similar couple months back

[jackssmirkingrevenge]

let me guess it looses to much gas before it seals? had the same problem when i attempted something similar couple months back

Spot on, should have known but anyway. Modded it, testing this afternoon.

edit:

under the "good" column:

WOOHOO!!! It worked at 10x, first click

under the "bad" column:

It blew the o-ring out :-/

Now, how to make it in such a way that the o-ring holds, yet is still plausibly replacable without taking the thing apart...

[ramses]

Now, how to make it in such a way that the o-ring holds, yet is still plausibly replacable without taking the thing apart...

Threaded fittings.

[jackssmirkingrevenge]

Threaded fittings.

I have high hopes for the latest prototype in 3/8", we'll see if they're justified or needlessly optimistic in a couple of hours

[jackssmirkingrevenge]

WIN!!!

It retains the bearing at 75 psi but pops at 90, so I'm restricted to a 6x mix, but even at such a "low" mix it flies back with considerable force, I think I would be willing to settle for this.

Here it is at 420 fps and real time, again the sound doesn't really convey how loud it is:

[youtube][/youtube]

Same shot at 1000 fps, note how the bearing ricochets off the leatherman and flies off dangerously towards the camera

[youtube][/youtube]

Now to make a breech and barrel setup to evaluate power and blowback potential I'm thinking short barrel XM-26 LSS style



Here is the cartridge with ammunition and a 12 gauge shotgun cartridge for comparison:

[Vonsproken]

Hi, Ive been looking through this forum for a few years now and have been waiting for someone to actually make a hybrid cartridge.

I designed two myself about 3 years back, a burst disk and one that retains a bb in a rubber seal.

The bb cartridge use a tap seal from the plumbing section, the bb popped out of it at about 80psi from what I can remember it lasted about ten shots before the seal wore, I simply unscrewed the front and placed another one it. It used a schrader valve to fill it. Only about 5cc.

My second design was designed to operate at over 60x, the burst disk was to be held by a screw cap. The filling was a piston design, when filling it is put into a jig, the jig pushes in the piston in to allow the gas in, when removed from the jig the pressure inside pushes the piston back and seals it. A piece of rod straight down the middle of the piston was the spark plug, although it would have to be operate by a flyback transformer. 6" long and 1" wide made from 316L stainless. 15cc

I scrapped the first cartridge a while back because I was afraid on it blowing up and decided not to build the second one as I sold my lathe at the time. You can only believe my word on it as I never showed any of it through the internet because I live in the uk.

It would be great to see multiple cartridges in a gun, good luck with your progress. Heating was a big problem for the barrels, mine warped from using thin walled tube. I still wish I could make this stuff but too paranoid of getting caught - was 14, no sense at the time, I'm just sticking to model engines