High pressure co-axial build log- updated 11/14/08

[Gippeto]

All metal co-axial design.
Piston to be piloted by a hammer valve.
"Bullpup" configuration to keep it short.

All tubing is 1026 DOM (Drawn On Mandrel)
All internals are 1045 annealed for machining

Barrel 36" 1"od. x .120" wall = .760" bore
Chamber 1.51"id.x1"(barrel od.)x10" (.120" wall) about 10 cu.in
Pilot area .062in2 (.280in dia) minimum throughout hammer valve.
Piston weight ~3 oz

Calculated burst pressure of chamber accounting for variations in wall thickness 9000psi - should easily take 3000psi (hpa)

Calculated shear strength of a single 1/4 x 28tpi socket head cap screw (using the lower YIELD strength) 3488 pounds of force (I'll be using 6 on the chamber front and 12 on the rear (hammer valve block).

Calculated burst pressure of check valve, 9000psi (using yield strength)

ggdt predicts good things

Anyone got a scuba tank for sale?

Finished piston.
Finished hammer valve.
Finished milling tube.
Finished barrel.
Finished check valve and barrel plug
Finished New check valve with probe style fill
Passed hydro testing. 6000psi for 3hrs.
Finished sear arrangement
Stock completed
Trigger group completed

Initial test firing demonstrated the need for a couple improvements.

New valve stem (teflon seat) and hammer spring (heavier)

Scope rail completed
New slug mold completed

Regulator arrived. Tescom 6000psi inlet, 2500psi outlet. Overhauled and re-ranged to 4000psi outlet.

Time to cast some slugs and punch some holes.


Test fire vid;

[youtube][/youtube]



Shooting vid;

[youtube][/youtube]

[SpudUke5]

wow looks great, especially your piston.

I expect great things from you

[Pilgrimman]

This is your 4th post, and you've surpassed my capabilities already! Needless to say, I'm impressed!

[jackssmirkingrevenge]

How did I miss this

Looking great, what's the estimated time of completion? Or at least, when are the test firings planned

[Skywalker]

Holy figgin krap dude! Nice machining, and that'll be a kickin' gun too! What kind of nice things does ggdt say?

[Gippeto]

Thank you sensei;

I'm currently re-doing the check valve.

While building the fill set up for the copper gun, I thought "Why not do a probe style fill? So much easier to get the trigger/sear around.)

If I can stop finding new distractions , it could be ready in a couple of weeks.


ggdt PREDICTS 500grain slug @886fps

[Antonio]

Nice work, awesome stuff. I wish I could make guns of this quality. I am looking forward to the results:)

[POLAND_SPUD]

ggdt PREDICTS 500grain slug @886fps

I think its power would be better used with 500 grams... anyway sorry for complaining - your gun looks very promising

[SpudFarm]

6000psi

that has to be an awesome gun

[Gippeto]

Thanks.

Time will tell whether ggdt is close on its estimate, I would certainly like it to be.

[pizlo]

... this is now my new favorite gun, even though its not gun it just looks so damn sick! and could you actually take it up to 6000? Where do you work??

[Gippeto]

Sick is good? 8) It will look similar to a bullpup assault rifle when done.

Not only could I take it to 6000psi, I did...for proving (see the pic with the gage). Designed operating pressure is 3000psi. All parts exposed to pressure have a minimum rating of 9000psi. (calculated using yield strength of the material)

"Where do you work?? "

Only the shadow knows!

[lockmanslammin]

>wipes drool from goatee<
WOW! This is the coolest thing I have seen on this site so far, hands down.
makes my current high of 315PSI look piddly. I am totally looking forward to some video. I bet it will sound like a d*mn real gun going off. This thing is a beast. H*ll you could probably hunt with the thing...lol.
Awsome..good work,

Lock

[jackssmirkingrevenge]

This thing is a beast. Hell you could probably hunt with the thing...lol

An 0.76" slug with 800 or so ft/lbs behind it is more than enough for most medium sized game if you can get to within 50 yards of it.

Gippeto, you do realise this thing has the potential to seriously harm your eardrums, I hope you've made provisions for some sort of ear protection...

[Gippeto]

White tailed "prairie carp"?

Accuracy will be the issue not power. A mold for foster slugs will have to be made.

No worrys on the hearing protection, I have it and generally use it.