High Pressure Copper Coaxial .22 Pellet Gun

[Gun Freak]

Here is a little video showing my new project. More pictures will follow.

Some specs:

Caliber: .22
Barrel: 36" of 1/4" OD .222" ID Brass
Chamber: ~11" 1/2 copper
Valve: barrel sealing piston
Piston composition: double o-ring cast epoxy, neoprene sealing face
Pilot: Blowgun
Fill: Schrader
Operating pressure: up to 300 psi (for now)
Primary Ammo: .22 lead balls and airgun pellets

[youtube][/youtube]

I just tested it with some tape-wrapped screws with blunt heads. They flew pretty straight and made very clean holes in a full 1L water bottle. At 40 feet it is very accurate with no sights. I missed the bottle once and the screw head got lodged into the wood fence so far that I couldn't get it out with my hand.

Updates and pictures to come when my scope and ammo arrive. Cheers!

[1nxtmonster]

Looking good! How many shots can you get out of one fill?

[Gun Freak]

Looking good! How many shots can you get out of one fill?

One... It's a standard coaxial piston valve, no hammer valves or anything like that. It is frustrating going from 30 shots/fill to 1, but its the price you pay for power.

[jackssmirkingrevenge]

It is frustrating going from 30 shots/fill to 1, but its the price you pay for power.

I see a hybrid on the horizon

[jrrdw]

Have you thought about soldering the stock on?

[Gun Freak]

Have you thought about soldering the stock on?

No and I won't do it because my soldering skills are horrible! Plus the stock needs to come off in order to service the piston.

Jack... no.

[Talk]

This is nice
looking at these nice pneumatic guns i feel like building mine

[Gun Freak]

This is nice
looking at these nice pneumatic guns i feel like building mine

Thanks!! You have one in progress?

[bravootome]

had you test it outside, at cold temperature? i noticed a large loose of power with my gun when the cold weather arrived.

[jackssmirkingrevenge]

I noticed a large loose of power with my gun when the cold weather arrived.

Lower temperature equals lower pressure, simple as that - some gasses are more affected than others though.

[Talk]

I need a spring for my air chamber and the price here to make a spring is too high so no ongoing progress right now.

[Gabriel S]

Nice, I really like the skeletal design. You could hook it up to run on a regulated Co2 power source, located in the middle of the shoulder stock.
Regards
Gabriel S

[hawktalk]

did you use something like this as a piston face
http://www.ebay.co.uk/itm/231086940827? ... 1438.l2649

[bravootome]

I noticed a large loose of power with my gun when the cold weather arrived.

Lower temperature equals lower pressure, simple as that - some gasses are more affected than others though.

In fact is not like that ! i still charge my gun with 30 bar rather cold or hot. it's the expansion of air fault. At cold temp the "explosion" is not the same, well on single shoot cannons you will not notice this effect but on multishoot the differance is like 300 fps. Still i am not sure if the piston work different at cold temp but it is involved in this power loose .

[Gun Freak]

'Tis always warm in sunny south Florida I would not notice a difference between 80F and 70F

@Hawktalk- I used a neoprene washer that I bought at the hardware store.

@Gabriel- That's a good idea but it involves a lot of money I have plans to run my 5lb co2 tank out of a backpack, unregulated. My calculations say it will drop about 4 psi per fill so I should get a decent number of shots per fill.