FiveseveN

OK, finally found time to work on the rifle a bit. So here's what happened :

I fixed a lil' design problem with the trigger and put it together, even completed the breech loader sys.
And then I got myself a car pump and it was time 4 testing...
But freakin' surprize when I herd the devastating hissing sound... yes... the valve leaked at exactly 40 PSI. Damn !
The problem is that I used the valve sys backwards (willingly, of course, so I can read the pressure and I can use the safety valve). Well, I figured that if it works one way, it should work both ways just as fine. But I was wrong.
So I spent the rest of the day figuring out how to use the sys without losing the ability to read the pressure off the gauge and to let the air out in case of emergency.
And imagination prevailed again... I had to use TWO such "valve guns",back 2 back, and that way I also solved the air tank problem.
The only problem now is that it really doesn't look like a rifle, so I need to think about integrating it into an appealing design fit for combat conditions.

You put it on top of the gun...
That IS the basic idea, isn't it ?

I do believe I know my own words and I believe I said "I bet some of the guyz here don't even know Pascal's law. "

And it's an elementary law, one that all of us take for granted, one without which nerfing, hidraulics, and God knows what else wouldn't exist.

But 'nuff of that. I just don't see what the big deal is. I mean... the pressure delta 'tween zero and 90 degrees F can be overlooked, it can be compensated by one or two more pumps. It's not like we're building Feinwerkbau grade airguns... it's freakin' foam...
Don't mind me, I guess I'm just too Eastern-European, doin' it the Russian way: build first and calculate later. ( And I wonder why there are more AK47s in the world than M4s ).

PS: I'm not a big fan of Automatik Kalashnikov.

5 to 1 ?! Man... Have you seen the episode in Scrapheap Challenge where they built huge air cannons with about 1.5 to 1 chamber to barrel volume ratio (the barrels were like one foot in diameter). And I've heard professionals talking about 1 to 1 ratio.
The thing is you can't just settle on a ratio. There are just too many variables, like you would wanna build up a lot of volume if you use an automatic gun (so you won't have to reload often) but if you have a single shot you might wanna use a small air chamber with lots of pressure (that way you don't have to work a sweat pumping).

PS: Don't anyone even think about calling me a newb, 'cause I've been in this field for like 4 or 5 years and I bet some of the guyz here don't even know Pascal's law.

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if you are using mostly steel tubing that you should be able to hold plenty of air pressure.

I doubt a 0.3 mm thick steel sheet can "hold plenty of air pressure" (I think that's about the thickness of the walls of a bug spray can).
Well, that's the thing : I've settled on 150 PSI ( 10.5 bar ) and I don't even think an average car tire pump can take that much ( maybe I'm just skeptical 'cause the M8F5 blew up in my face once and that was only 4.2 bar ). The thing is I've blown serious firecrackers in aluminum pipes, made plastic and cardboard flamethrowers and now I only wanna make something a lil' safer for me...
Haven't had the time to work on the rifle this week and I don't think I will any time soon. But I've one idea for a small air chamber so things are looking up. Stay tuned.