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Spring Piston Air Rifles?

This area is for the discussion of BB or airsoft sub machine guns, and or other small arms such as pellets.
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Spring Piston Air Rifles?

Unread postAuthor: jmez1996 » Fri Jan 13, 2012 3:51 am

Hi again Spud files community, haven't posted in a while since i've been busy with school and holidays but i have another question to put to everyone here.

Why is there such little time put towards homemade spring piston air rifles? ones that work on similar mechanism's to the store bought air rifles.

I understand pneumatics can be a lot more powerful and allows for faster shooting but i like the compact, no pump required feeling of a spring piston air rifle.

Im thinking of making one with an old bike pump as the primary piston.
Can anybody suggest any good examples of ones that have been made?

thanks again :)
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Unread postAuthor: jackssmirkingrevenge » Fri Jan 13, 2012 4:12 am

some of the usual objections here:

http://www.spudfiles.com/forums/spring- ... 18133.html

The only benefit of a springer in my view is that they are self contained, because compared to pneumatics they:

- are noiser
- are much more difficult to shoot accurately
- require very strong construction even for low power levels

My suggestion would be to make a pneumatic with an on-board pump.

Have a look at the Crosman 1337:

Image

It uses a tiny chamber which can be brought to high pressure with a small number of pumps, enough to give decent power - indeed more than a similarly sized spring piston pistol could hope for, and with much less recoil too.

If you replace the hammer valve with a QEV you'll get even better performance.
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Unread postAuthor: jmez1996 » Fri Jan 13, 2012 4:46 am

Yeahh thanks that looks like it could work. The main task would be sorting out a pump that works on that mechanism to get more leverage over a straight pump.
How would this go with a QEV instead of a hammer valve?
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Unread postAuthor: jackssmirkingrevenge » Fri Jan 13, 2012 5:04 am

jmez1996 wrote:The main task would be sorting out a pump that works on that mechanism to get more leverage over a straight pump.


You could still use a straight pump, but make the piston smaller diameter. Think shock pumps, they have a much smaller diameter than a tyre pump but can get higher pressures with the same effort.

How would this go with a QEV instead of a hammer valve?


Just like any pneumatic, but with a relatively small chamber (1:1 ratio should be more than enough for a high pressure launcher) and a pump fitted.

Hmmm, if only I could think of an example of a QEV launcher.
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Unread postAuthor: jmez1996 » Fri Jan 13, 2012 9:51 am

Ahaha oh you ;)
Well thanks ill see what i can come up with over the next few weeks :)
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Unread postAuthor: Brian the brain » Fri Jan 13, 2012 2:30 pm

After JSR has so gracefully convinced you NOT to try a springer I feel obliged to complete the pro/con story .

1: As a springer is fired it compresses air.This produces the air to heat up, wich can yield higher muzzle velocities than a PCP pneumatic could because in a PCP the reverse takes place.Stored air expands and cools.
Hot air can move faster than cooled air.

2: based on the workings above, a springer can be used to ignite fuel in the chamber known as dieseling.This will create even hotter gasses and more volume of it.
Supersonic velocities just became the norm.

3: obtaining and precompressing a powerful spring is supposed to be practically undoable....unless you use an airspring.

This could be installed without any prior compression and then afterwards be tailored to the shooters bodystrength.
In other words, fill up that airspring to the maximum pressure required so that the shooter can only just manage to cock the launcher.

With a longer barrel the system would be easier to cock, so enlarging the conventional design will give you more power than a commercial springer, without more effort.
Granted, the stroke would be longer, requiring more energy input, but at no point would it exceed the shooters capabilities.
A 9mm version , maxed out on springforce with a long barrel and a drop of suitable fuel would probably be not so weak...

Anyway, I just finished a pump-pneumatic...so what do I know.. :D .

The principle is nothing to sneeze at, but indeed building one requires skill, specific tools and suitable materials.
That is why it is out of the newbie realm.

Edit:
Furthermore: An airsping could be MUCH more powerful than a steel one.
Look at this basic principle:
When you compress a short airspring by 2 inches, the pressure builds up significantly.
Now in comparison compress a really long airspring those same 2 inches.
The pressure won't rise as much.

The stock of a conventional springer is little more than the remains of a dead tree...or a non biodegradible chunk of hydrocarbonates if you lack taste....
So..

Forget the wood or plastic stock and replace it by a reservoir pneumaticly connected to the airram/airspring.
Now preset the pressure like I proposed before.

Now you get a "main spring" that is able to push almost just as hard at the end of the stroke as in the start of it.
Compressing it won't be significantly harder but it will give you a much more powerful shot.

I plan to build one in this way this year,it will be just one of my upcoming projects.
And this is my longest post ever!
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: jackssmirkingrevenge » Fri Jan 13, 2012 3:22 pm

Brian the brain wrote:After JSR has so gracefully convinced you NOT to try a springer I feel obliged to complete the pro/con story .


BOOOOOO!

1: As a springer is fired it compresses air.This produces the air to heat up, wich can yield higher muzzle velocities than a PCP pneumatic could because in a PCP the reverse takes place.Stored air expands and cools.
Hot air can move faster than cooled air.


True... but you need one heck of a spring before this becomes an advantage.

2: based on the workings above, a springer can be used to ignite fuel in the chamber known as dieseling.This will create even hotter gasses and more volume of it.
Supersonic velocities just became the norm.


... as does wildly inconsistent velocity, and the possibility of destroying the thing from too much fuel...

Lets look at some fine British engineering:

http://www.theoben.co.uk/files/ba_dm.pdf

Theoben Dual Magnum, one of the most powerful gas rams out there, 36 ft/lbs in 0.22" - beautiful piece of craftsmanship, I certainly wouldn't turn it down...

http://www.daystate.com/air-ranger.htm

Daystate Air Ranger, 60 ft/lbs in 0.22"

Hmmm...

The principle is nothing to sneeze at, but indeed building one requires skill, specific tools and suitable materials.
That is why it is out of the newbie realm.


... so the point still stands.

That being said, I eagerly look forward to seeing a "rough" gas ram from your stable :D
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Unread postAuthor: Brian the brain » Fri Jan 13, 2012 4:02 pm

That being said, I eagerly look forward to seeing a "rough" gas ram from your stable


I'd be interested to see if any of my proposed changes to the traditional ones will improve it... :D
The most critical factor you're skipping over is volume.
You should be comparing a springer to a Brocock cartridge
or compare my idea with a full reservoir PCP.


I intend to up the volume of the airspring to a massive scale.
This will keep pressure high untill the ammo leaves the muzzle and leave enough for a loud bang...
At least...that's the theory.
Conventional airspings usually replace mechanical springs and are confined to the same volume.
This puts restrictions on the force applied at the end of their stroke as they couldn't be compressed otherwise.
Then use a barrel 1.5x the traditional length to help overcome even more force..

I'm not joking.
Volume is why a spudgun easily outdoes a commercial airgun...or even some firearms.
When it comes to upping the power there is no easier substitute than the American way.

So a 9...make that 10 since I have the balls. mm springer I can only just cock with all my strength and weight...and momentum combined..

Then diesel it... :D

That would just be worth the effort..
Who cares about wildly inconsistant velocities when the sheer size of it is epic muhahaha
LOL.
At least it would become a SF classic

Anyway...you see the airram is the way to go if you want "the most powerful" springer.
Plus I am eager to find out if upping the caliber and chambervolume will increase it's power.

Anyway...just learned about a coaxial-built in pump airgun made by Bate in the Girandoni era...
that kinda distracts me at the moment...wish I could find more about it..
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Last edited by Brian the brain on Fri Jan 13, 2012 4:23 pm, edited 1 time in total.
Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: jackssmirkingrevenge » Fri Jan 13, 2012 4:08 pm

Brian the brain wrote:Anyway...just learned about a coaxial-built in pump airgun made by Bate in the Girandoni era...
that kinda distracts me at the moment...wish I could find more about it..


Image

There's one in the Beeman collection, second from right.

http://www.beemans.net/contact_us.htm

;)
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Unread postAuthor: Brian the brain » Fri Jan 13, 2012 4:28 pm

Cool or what!?!?!
:D

That is my source...yes..
But my experience with those kind of companies is that they only reply to commercial questions.

I have edited (and added to) my previous post concerning the springer versus PCP debate.

Not that I would ever win a battle of whits with you... :wink:
I can always end it by asking why you're not building something spectacular now you no longer have an excuse
.. :lol:
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: jackssmirkingrevenge » Sat Jan 14, 2012 7:58 am

Brian the brain wrote:Not that I would ever win a battle of wits with you... :wink:
I can always end it by asking why you're not building something spectacular now you no longer have an excuse
.. :lol:


Oh ye of little faith... things are moving behind the scenes, more in future ;)
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Unread postAuthor: Brian the brain » Sat Jan 14, 2012 10:15 am

Since you do not contradict my assumptions....does this mean you agree...or don't know...

or have given up trying?
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Gun Freak wrote:
Oh my friggin god stop being so awesome, that thing is pure kick ass. Most innovative and creative pneumatic that the files have ever come by!

Can't ask for a better compliment!!
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Unread postAuthor: Hawkeye » Sat Jan 14, 2012 10:39 am

I have an old "Guns Annual" or something like that that shows a diagram of the Bate airgun.
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