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| Gippeto |
 Posted: 01/20/2008 23:20 PM Post subject: High pressure co-axial build log- updated 11/14/08 |
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Colonel
Joined: 19 Jan 2008
Posts: 705
1746.17 Spud Bux
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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;
http://www.youtube.com/watch?v=d1RQnTd8D1w&feature=email
| Description: |
| The end of the road for this thread. FINISHED. Test firing to start as soon as time allows. |
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| New split mold. A huge improvement. |
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Reworked my slug mold. New Foster slug comes in @ 550 grains. "Skirted" slug is 520 grain.
.177 swiftflite and .22 Benji dome for comparison |
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| Slug came out at 830 grains. Far heavier than I wanted. Will make some changes to reduce the weight and improve the mould.( its a bugger to get the slug out, need a split mould) |
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| Finished my new check valve with probe style fill. Plug and play. : ) |
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| Passed hydro like 6000psi was nothing! |
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| Rear plug w/spring seat, spring and hammer, Hammer valve, piston, ring to be sectioned for centering of barrel, Quad ring |
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Last edited by Gippeto on 11/14/2008 18:48 PM; edited 22 times in total |
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| LikimysCrotchus5 |
| Posted: 01/20/2008 23:22 PM Post subject: |
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Brigadier General
Joined: 04 Sep 2007
Posts: 1064
2535.08 Spud Bux
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wow looks great, especially your piston.
I expect great things from you
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| Pilgrimman |
| Posted: 01/20/2008 23:41 PM Post subject: |
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Lieutenant Colonel
Joined: 28 Jun 2007
Posts: 433
925.14 Spud Bux
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This is your 4th post, and you've surpassed my capabilities already! Needless to say, I'm impressed! 
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| jackssmirkingrevenge |
| Posted: 03/26/2008 12:32 PM Post subject: |
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space monkey
Joined: 15 Mar 2007
Posts: 7050
11306.91 Spud Bux
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How did I miss this 
Looking great, what's the estimated time of completion? Or at least, when are the test firings planned
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| Skywalker |
| Posted: 03/26/2008 12:40 PM Post subject: |
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Sergeant First Class
Joined: 05 Aug 2007
Posts: 138
514.57 Spud Bux
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| Holy figgin krap dude! Nice machining, and that'll be a kickin' gun too! What kind of nice things does ggdt say?
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| Gippeto |
| Posted: 03/26/2008 12:41 PM Post subject: |
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Colonel
Joined: 19 Jan 2008
Posts: 705
1746.17 Spud Bux
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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
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| Antonio |
| Posted: 03/26/2008 13:04 PM Post subject: |
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Captain of Industry
Joined: 13 Aug 2006
Posts: 495
24.52 Spud Bux
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| Nice work, awesome stuff. I wish I could make guns of this quality. I am looking forward to the results:)
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| POLAND_SPUD |
| Posted: 03/26/2008 15:49 PM Post subject: |
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Brigadier General
Joined: 13 Oct 2007
Posts: 984
2470.13 Spud Bux
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| Quote: | | 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
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| SpudFarm |
| Posted: 03/26/2008 16:29 PM Post subject: |
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Hybrid Guy
Joined: 04 Nov 2006
Posts: 2097
1187.34 Spud Bux
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6000psi
that has to be an awesome gun
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| Gippeto |
| Posted: 03/26/2008 18:53 PM Post subject: |
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Colonel
Joined: 19 Jan 2008
Posts: 705
1746.17 Spud Bux
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Thanks.
Time will tell whether ggdt is close on its estimate, I would certainly like it to be.
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| pizlo |
| Posted: 03/26/2008 19:14 PM Post subject: |
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Colonel
Joined: 22 Dec 2006
Posts: 659
951.19 Spud Bux
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| ... 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??
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| Gippeto |
| Posted: 03/26/2008 19:27 PM Post subject: |
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Colonel
Joined: 19 Jan 2008
Posts: 705
1746.17 Spud Bux
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Sick is good?  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! 
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| lockmanslammin |
| Posted: 03/26/2008 22:24 PM Post subject: |
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Staff Sergeant
Joined: 10 Feb 2008
Posts: 123
511.95 Spud Bux
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>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
Last edited by lockmanslammin on 03/27/2008 10:01 AM; edited 1 time in total |
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| jackssmirkingrevenge |
| Posted: 03/27/2008 0:07 AM Post subject: |
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space monkey
Joined: 15 Mar 2007
Posts: 7050
11306.91 Spud Bux
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| lockmanslammin wrote: | | 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...
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| Gippeto |
| Posted: 03/27/2008 8:25 AM Post subject: |
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Colonel
Joined: 19 Jan 2008
Posts: 705
1746.17 Spud Bux
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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.
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