New to PCP need advise

[shady816]

I have been into spring guns for a long time and for some crazy reason the other day I decided I was going to build a pcp rifle from scratch. I have been reading and taking notes as well as looking at breakdowns of all the guns I could find just to start getting the whole picture. Now I dove in head first and have most all the materials on the work benches and started working on the breach and bolt and new LW barrel. So now is when the questions start...what would be the best material for a pressure tube I do not want a tank hanging from the gun and if someone could inform me of what the operating pressure should be for a powerful pcp.I was thinking of 304 stainless until I read 4130 steel was stronger per square inch so what is the normal metal used and did I forget to say I know nothing about pcp,hpa,co2 but I am a mechanical engineer and can design build just about any crazy contraption that I come up with, with a little advise. the area I will be needing the help is the fitting styles and thread styles for end caps and such as well as valve info I was thinking of cutting thru the BS and just going with a modified valve from a custom mod already available for purchase.i have seen several thru a number of Internet searches that would appear to have good potential design as far as flow and seal though I could remake one if need be to fit a larger or smaller tube .So come all ye modders and feed me input input input and I promise to give a full detailed photo by photo of the progress and I'm sure I will have more questions. thanks in advanced for your help.  Robert.

[kiwi]

4130 "chrome-moly" is light weight ,,but I would use a seemless tube..ie boiler tube, it
will have a lot thicker wall but can be machined thiner...Why not use a 13 or 22ci bottle
Theoben / BSA style..

[shady816]

yes the 4130 chrome moly is what i will most likely use but i see the 22xx tubes out there and that would allow me to buy a modified valve pre made but would be affraid it would not produce what i want for fps. i am looking to produce a 900 fps + .22 cal gun is that asking way to much again i am new to the pcp game.my design look will not allow the use of a bottle at 2" diameter would be to big so i will need to manufature a tube that will hold up to 3000-4000 psi (is this possible) i would think so since i have stumbled across many claiming to have done it.i really need a good lesson on the psi needed plus the valve vs. hammer pin weight i get a feeling i will or may achieve what i want for fps but will suffer only a few full power shots on a fill up, it will be used for hunting purposes so as long as i can get 10-15 good full power shots i will be fine with that. as far as filling it up, i own and run a hvac buisness and have way to many nitrogen tanks around as it is so no pump will be needed.thanks for the reply

[DaveShooter]

hey if ya get that baby built show or post some pictures of her or him!!!!

[shady816]

it will get built for sure...i think after recent searches and part finds i just may be using several parts that are available on the market such as breech and valve but the rest is up to me and the butt stock arrived today so sweeet.