SpudFiles

Judgment Arms Automatic Cannon XM001A1:

Caliber: 1.25cal/ 32mm
Operating mechanism: Blish delayed blowback
Main Valve: 1.5” piston “tee” valve
Pilot Valve: 1” modded sprinkler valve
Barrel length: 36”/ 29calibers
Pressure Reservoir volume: 48in^3

Muzzle velocity: les than100fps
Effective range: N/A
Max range: 30yards

Yeah, it’s plain to see why I consider this a flop: it has no power what so ever.
When it works (cycles) it shoots a “bullet” (made from a ¾” end cap a ¾”coupler and a ¾”plug, I’ll get a picture latter) about 10 feet… when it fails to cycle I’ve had one round go near’e 30 yards…

I call it the Wookie gun because I hade a piece of crap sprinkler valve that honked when you charged it, it literally sounded like a Wookie!

The original model had no delay mechanism and cycled 90% of the time. The A1 (the one pictured) has a piece of coupler in the chamber (not the pressure chamber) that the rounds plug into, the friction of pipe on pipe delayed it enough to get something worth calling performance, but at the cost of reliability as now it only cycles 50% of the time

I’ve also shot paintballs out of this thing and at 10 feet, with the original model I’ve had the paint break about 20-35% of the time, with the A1 it breaks about 10-20% of the time, go figure…

The charge handle in the pictures is actually the piston rod from an old water pump I made; the original charge handle is lost.
Also the “Wookied” valve is being used on the prototype I’m working on.

Any Questions or comments?

100 fps? No problem.
Remember, if it doesn't work, use more power!

How does it eject the casings? Sorry but I'm a very visual-type learner.
Maybe some mspaint scribbles would help.

_Fnord,
100fps is being optimistic, all my figures were. I was running it at 120psi which is the max my compressor will put out

As for ejecting, the round is pushed back by the gas from firing and when it gets so far back it just drops, it’s that simple; I’m getting ready to go work on my prototype but if you need a visual I’ll work on it later, once it’s to hot to be out side.

Well, even if its not soo great working, it still looks really good
Are you still going to work on it and try improve the performance?

EDIT: just got my answer from your above post

Spud Yeti, I believe you, and most likely a few other people, have bean confused; this is not the prototype I’m currently working on, this one has bean relegated to the boneyard, between the time I took the pictures and now I’ve already removed part of the valve assembly.

I thought I’d post it so people know what NOT to do.

Oh, OK; yeah there was a misunderstanding there. Oh well, at least you know what not to do now

Nice effort, clad to have been of some inspiration

I can understand about the low power, it's what put me off pursuing my own project in the first place - however, subsequent analysis of my design showed that the breech was in fact too short, with a bit more length and chamber volume it would doubtless have been more effective - I'm still pondering whether I should re-visit the idea, given the dubious progress with my preloaded cartridge prototype.

Well the only thing I’ve figured out that the only thing I could do to make it work better is to either shorten the barrel or lock the breach shut, which I may just do to see what kind of power I can get out of this sucker…

@jsr: what exactly would a longer breech stroke do

@ judgment arms: wouldn't shortening the barrel allow gas to escape quicker and air to escape sooner thus giving the blow back force less time

I’ve also shot paintballs out of this thing and at 10 feet, with the original model I’ve had the paint break about 20-35% of the time, with the A1 it breaks about 10-20% of the time, go figure…

wasn't the A1 made to have more power and less reliability? then why does it have more trouble breaking paint balls

iknowmy3tables wrote: @ judgment arms: wouldn't shortening the barrel allow gas to escape quicker and air to escape sooner thus giving the blow back force less time

If the bolt opened before the projectile left the barrel, then it would improve the projectile’s performance

wasn't the A1 made to have more power and less reliability? then why does it have more trouble breaking paint balls

I believe part of the problem was that the piston valve was slowly dieing, I don’t quite recall exact performance with paint in the A1, but I do know that it would throw a PVC slug about twice as far as the original.

For the record, the piston valve is completely seized up, even if I wanted to revisit this I couldn’t with out diverting precious and highly limited funds from my other projects

If the bolt opened before the projectile left the barrel, then it would improve the projectile’s performance

are you sure you said that right, I'm pretty sure thats why so many guns have been designed with delay mechanisms

No you see, I’m say that, if the bolt opens before the projectile leaves the barrel, then shortening the barrel would improve performance because the projectile wouldn’t be slowed down by barrel friction.

okay, well I guess compared to the chamber it would be good to shorten it but only a little because the barrel is not the cure, but before I say anything pointless what are you changing in your current prototype?

the "XM001A1" label, I see you're mimicking the US military naming, including the "X" part for experimental, but the detail you left out is the "A" thats suppose to be an "E" because it's experimental

iknowmy3tables wrote:okay, well I guess compared to the chamber it would be good to shorten it but only a little because the barrel is not the cure, but before I say anything pointless what are you changing in your current prototype?

None of my current prototypes are blow-back, they’re recoil and/or gas operated.

the "XM001A1" label, I see you're mimicking the US military naming, including the "X" part for experimental, but the detail you left out is the "A" thats suppose to be an "E" because it's experimental

I’ve never seen the “E” designation, only “A”.
Usually on “XM” designated weapons any upgrade gets a new designation, so technically this should be the “XM002”.

hmm looking at some other examples I could be wrong, "E" could just mean a variant instead of an experimental upgrade, examples I know are the M60E1,2,3, and 4