14mm Automatic Air Rifle

[inonickname]

Infact, now I see the work that's gone into this I want one. Rather than using a solenoid valve I'd use a mechanical spool valve or sleeve valve. I'd also so it in around .38 caliber.

I just need a good way to get projectiles. I could turn down a 10mm rod and use that or make a split mold and cast.

Would you mind if I used some of the ideas from this in my gun? I just need the ammo really..

[al-xg]

A mechanical 3/2 valve or even a (less efficient) regular blowgun with restrited fill rate works fine.


Although well made bullets will perfom better, you could also use spherical projectiles.
The few shots I did that reached out to 200m were with lead round balls (14mm round fishing wheights pressed shut).
As seen here:

[Moonbogg]

Any chance of a video of it shooting?

[POLAND_SPUD]

I see the work that's gone into this I want one

uhmmm right now I am building something similar... hmm it would be cool to have a couple of different designs being developed at the same time...

sort of like... unofficial community project

The spring pushing the ferrous solenoid core against the seat will only hold it to about 400psi

same here but most leaks on mine are caused by a small ring that is tilted by the mechanical override lever when you use it... somehow fast flow of air dislocates it from, time to time

[al-xg]

Sadly, probably not until some time in december.

I ended up blocking off the manual overide when casting the epoxy, but it can still be uncovered if needed.

How bout using a microswitch on the air ram instead of a timer to get full auto on your design ?

[inonickname]

What was your C:B ratio (on firing). I'm not sure if the full length of that pipe is used each shot.

[al-xg]

The chamber volume is 160cc (including fittings and inside the QEV).

The whole barrel is 110cm long by 14mm ID, so 169cc.
The gas piston has a 20mm ID and the stroke must be about 5.5cm, so about 17cc
The QEV dead volume is probably around 14cc.
And the 3/4" T about 21cc.

So the C:B is approx 7:10

[Ragnarok]

Let's see 'em then.

You'll see them when I'm about ready to use them.

Given I've designed them with the purpose of setting a few records, it would be a bit silly giving away the specifics until after I'm done - so I'd like to keep the details to myself until things are near completion.

[pipeboyswe]

Wow really awesome gun 8) cool with blowback

[Brian the brain]

I've been thinking about this rifle for the past couple of days..

The boltpiston could be made coax, so it is a lot cleaner.The rod could be replaced by a moving barrel sleeve.
The boltlock could be reworked so it works with only one rod by placing the lock on the bolt itself...

This system has so much potential!

[inonickname]

I've decided I'm building this..

Problem being, I don't have blocks of aluminum to machine each part from. Though I do have nylon in appropriate sizes which is easy to work and cheap. I'm hoping I can make each part as I want it from nylon then use something like the lost wax replacement casting method with aluminum. Would this work?

Nylon melts at 190-350 celsius and I'm casting the aluminum at 700 celsius plus.

[Brian the brain]

The Nylon won;t pour out cleanly.It will most likely burn and gum up the mold.

Why would you choose not to use wax?

Did you read the coax comment? it would clean things up a lot.

[al-xg]

I did consider using just one rod, and have the bolt guide on the other side behind the bolt lock. Actually I didn't have time to make a new bolt and am still using the first one I made. The cut in the side for the bolt lock to latch on to is just visible on some of the pics.

I did also like the idea of a coaxial piston and sleeve, like on the FX monsoon. But seeing the way the quality of my build turned out, I think I would have had too many losses through friction


Why don't you just cast the aluminium blocks and then machine them ?

[inonickname]

The idea with nylon is that I could essentially put the gun together, make sure everything works then make replicas of each part. I'd rather not make it co-ax, I believe if done cleanly the side by side blowback would look good.

I'll just prototype each part in nylon then order some aluminum stock I suppose.

[Pookydarts]

Although well made bullets will perfom better, you could also use spherical projectiles.
The few shots I did that reached out to 200m were with lead round balls (14mm round fishing wheights pressed shut).
As seen here:

Those projectiles look great!
Next time you get your hands on your gun try sending some up the barrel backwards!

edit: ...So much for showing off my computer skills... try this:http://members.shaw.ca/cronhelm/SubsonicBullet.html