.25 cal Coax Rifle

[maverik94]

Ok, I actually built this gun about 8 months ago. It was my first successful piston-valved gun after my unseccessful pengun prototype:


Anyway, here are the specs of the gun:
Chamber: 8" x .5" Steel Nipple
Barrel: 34" x .3125" (5/16") O.D. (.26" I.D.) Brakeline
Valve: .5" Coaxial Barrel-Sealing Piston Valve
Piston: .45" Brass Pipe filled with epoxy and wrapped with masking tape and a truck-tire inner tube sealing face
Fill Valve: .125" (1/8") Brass MIP threaded schrader valve
Pilot Valve: Heavily Modified (Internally and Externally) Husky Blowgun Valve
Primary Projectile: .22 cal Hollow Point Airgun Pellets

Anyway, I built this gun a while ago and used it heavily for a month or two until the epoxy sealing the barrel developed a crack, I then repaired that, but it cracked again not long after. I concluded that this was because of the lack of a barrel support. After the second crack in the epoxy I discovered that the barrel had been bent a considerable ammount, and decided to scrap the gun, it is no longer in existence in its completed form, the parts are employed in various other guns or are residing in my spares box. As far as power, i was impressed with the coaxial piston valve's efficiency and I finally understood why all of you urged me to build one . I shot it through a chronograph at 120 psi and got a little more than 300 fps. However, I have pumped this gun up to 350 psi and gotten much more power (but sadly I never measured the power with higher pressure). Also, I was using a .22 cal airgun pellet as my ammo because I couldn't find any more suitable ammo, so that cut performance considerably. The gun easily shot through both sides of a steel cambell's soup can at 300 psi. The stock is made from yellow pine, which is nice wood, but it splits a lot, I prefer poplar. I made it using only a jigsaw, circular saw, and a hammer and chisel. I stained the stock with some Minwax (I think) stain and I added some extra pigment to darken it. Anyway, thats about all I have to say about this gun. Sorry for writing a book about it, but I get into this kind of stuff, you know?

Anyway, for pictures:
Three pictures of the complete gun:




Two pictures of the gun without the stock:



The piston I used:


A steel Cambell's Soup can I easily shot through at 300 psi:

Hope you enjoyed!!!
(WOO HOO!!! 400th POST!!!)

[POLAND_SPUD]

wow I see that the quality of your work improves really fast...
I like it

[Marffy]

Thats a great gun. very good quality. i hope to see a break barrel.

[maverik94]

wow I see that the quality of your work improves really fast...
I like it

Thank you! I do my best

i hope to see a break barrel.

Are you referring to the one mentioned in my signature? If so, it is not a coaxial like this, it has a kind of piston valve that hasn't been done before on spudfiles (except once). And I can't wait to see it either!

[chinnerz]

wow that looks like a better version of my rifle!! however, i have to ask, is that thumbhole comfortable?
If it is, that great!!
if not, and if you don’t mind, i would like to make a suggestion. Buy yourself a rasp, (essentially the files angry arsed brother) and make the hole a bit longer, while tapering in the edges, and just clean it up with a file/ sandpaper. A rasp will set you back $(A) 20.00, will last half a life time, and is a very useful tool to have.
http://www.thesaddleryshop.co.uk/Admin/ ... c3415b.jpg

[jackssmirkingrevenge]

Oooh very nice, needs a sight for completeness though, as well as an integral suppressor, it will make it quieter and remove that skinny look

[chinnerz]

as well as an integral suppressor, it will make it quieter and remove that skinny look

yeah it will definitely add appeal to your rifle.

[maverik94]

wow that looks like a better version of my rifle!! however, i have to ask, is that thumbhole comfortable?
If it is, that great!!
if not, and if you don’t mind, i would like to make a suggestion. Buy yourself a rasp, (essentially the files angry arsed brother) and make the hole a bit longer, while tapering in the edges, and just clean it up with a file/ sandpaper. A rasp will set you back $(A) 20.00, will last half a life time, and is a very useful tool to have.
http://www.thesaddleryshop.co.uk/Admin/ ... 4897-8bed- e4a1f0c3415b.jpg

Yes, it is quite comfortable surprisingly! And yes, I do have a rasp, in fact I have 3 of them! However I prefer to use sandpaper on yellow pine because it splits so much!

Oooh very nice, needs a sight for completeness though, as well as an integral suppressor, it will make it quieter and remove that skinny look

I was planning on that, but sadly, as stated above, the rifle is no longer in existence

[IMagius]

Very clean and good looking build.

One thought from the Mechanic in me ... Since you are using brake line for the barrel, why not use a flare tool and a brake line coupler for attaching the barrel to the chamber? It would elimiate the need for the Epoxy and remove a "weakness" from the design.

No need to buy the Flare Tool either - if you ask around, some places like Napa will let you borrow those types of tools for a day or two if you buy the Line/Fittings there.

[Hawkeye]

But then the barrel won't extend back into the chamber.

[maverik94]

One thought from the Mechanic in me ... Since you are using brake line for the barrel, why not use a flare tool and a brake line coupler for attaching the barrel to the chamber? It would elimiate the need for the Epoxy and remove a "weakness" from the design.

The only problem is:

But then the barrel won't extend back into the chamber.

I have the entire flaring/cutting kit, and I thought about this, but As far as I know, there is no simple way to get around this.

[jackssmirkingrevenge]

As far as I know, there is no simple way to get around this.

Other than using decent epoxy?

[maverik94]

maverik94 wrote:
As far as I know, there is no simple way to get around this.

Other than using decent epoxy?

I meant getting around using the epoxy. Ant though I know this is sacreligious to you JSR, I have to say that I like to use as little epoxy as possible.

[Marffy]

wow I see that the quality of your work improves really fast...
I like it

Thank you! I do my best

i hope to see a break barrel.

Are you referring to the one mentioned in my signature? If so, it is not a coaxial like this, it has a kind of piston valve that hasn't been done before on spudfiles (except once). And I can't wait to see it either!

yep, i'm reffering to the signature. I hope to see any break barrel pneumatic gun. I think it should be a double barrel. that would be awesome.

[maverik94]

yep, i'm reffering to the signature. I hope to see any break barrel pneumatic gun. I think it should be a double barrel. that would be awesome.

A double-barrel eh? ....it could happen