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Hellbender
10-17-2003, 02:40 PM
I know this was done a long time ago (Lewis and Clark killed Elk with one) and I would like to build a modern version.

Been planning this for several years in my mind, but I'm too dumb to answer some of my questions......

What I'm planning is roughly as follows...

Small (3.5" Dia. x 12" long or so) 2800 psi oxygen bottle for the buttstock (open to other suggestions).

Barrel...smoothbore (to reduce friction)possibly a .410 shotgun bbl with rifled choke tube.

Shooting a saboted projectile (?).

How much will bbl length affect velocity?

What would I be getting for muzzle velocity with say a projectile weight of 100 grains or so (including sabot) per inch of bbl?. I'm hoping to get 1000-1200 ft per second out of an 80-90 grain projectile (after sabot discards).

What would be a cost effective way to release the gas pressure for the length of time it takes the projectile to leave the bbl?

Maybe I would be better served with a 30 cal barrel shooting commercially available sabots for .224 bullets........

I'm sure more questions will arise as the discussion ensues.

Thanks,
HB


[This message has been edited by Hellbender (edited 10-17-2003).]

Evan
10-17-2003, 02:51 PM
You might like to read this previous thread:

http://bbs.homeshopmachinist.net//Forum1/HTML/003764.html

Dr. Rob
10-17-2003, 03:02 PM
Why is barrel abbreviated, "bbl"? Or is that something else, like breech block?

tonydacrow
10-17-2003, 03:23 PM
Hellbender,

I'd use CO2 rather than O2... Unless you wouldn't mind the rifle occasonally becoming a flame thrower. HEY..., how about using mixed gases and a heat source to increase the speed of the projectile with combustion?

Dr Rob,

I've always thought bbl meant "bull barrel" indicating the lack of taper on a thick barrel.

Evan
10-17-2003, 03:26 PM
Actually, for that pressure CO2 will liquefy. Use simple compressed air and recharge from a scuba tank.

JCHannum
10-17-2003, 03:46 PM
bbl. is the abbreviation for barrel for the same reason that lbs. is the abbreviation for pounds, or that Mrs. and Ms. are the abbreviations for no real words at all.

Hellbender
10-17-2003, 03:48 PM
Evan, thanks for the link, I had watched that thread a while back.

Dr. Rob, good question, I have always known it to be for "barrel"....another question....why is pound abbreviated lb.?

tonydacrow, as Evan states, the CO2 will not attain those pressures without liquifying, I can recharge high pressure air from a scuba tank easily.

Thanks,
HB

Edit: I see JC beat me to the lb. thing!

[This message has been edited by Hellbender (edited 10-17-2003).]

bikenut
10-17-2003, 03:48 PM
Do you live in Canada? Why mess with an air rifle when you can have a real gun? One thing I love in America is the right to KEEP & BEAR ARMS. WHEN FREEDOM IS OUTLAWED, ONLY OUTLAWS WILL BE FREE. It's worth dying for. "Give me liberty, or give me death" Patrick Henry. "When there's nothing worth dying for, there's left to live for." Me, Later, Smitty

Hellbender
10-17-2003, 03:53 PM
bikenut..... No, I'm in Missouri, and I have a bunch of guns, and high-power airguns.

But I don't have an airgun that could kill a deer at 100 yards, and I don't know of anything commercially available, but I know it can be done, and I would like to figure out how.

bikenut
10-17-2003, 04:33 PM
Hellbender, To have enough power to kill at 100 yards you would have to have a decent size projectile, like a .270, with a hell of a lot of air pressure to push it out that far and still have enough energy to knock something down. I'm living in Iowa right now, what a ****ty nanny state this place is. Came from Arizona where you can carry a gun all day every day, can't wait to get the hell out of here. This place is like the rest of the "civilized" world where the government want's to do all of your thinking for you.

Evan
10-17-2003, 04:33 PM
HB,

Have a look at this guy's stuff.

http://www.barnespneumatic.com/index.html

BTW pound=lb= Latin "libra"

[This message has been edited by Evan (edited 10-17-2003).]

Yankee1
10-17-2003, 04:40 PM
Hello
Check out these airguns at:
"www.glbarnes.com"
I think you will find the information usefull.
Yankee1

Yankee1
10-17-2003, 04:46 PM
Hello Again
And while were on the topic check out:
"www.connext.net/~daq/index.html"
As you can see I share your interest in
airguns. I shoot all kinds of weapons but
shoot airguns more than anything I own.
I shoot about 20,000 pellets a year. Sometimes more.
Yamkee1

bikenut
10-17-2003, 04:53 PM
Evan, that guy does some beautiful work, but I think I'll stick with my '06. I can bust a "light stick" at 200 yards at night. Thats the kind of shooting me and my brother used to do when we went camping out in the sticks in Washington state. I checked into moving to Canada, could just make the cut as a skilled worker. Checked into the gun laws, to me it ain't worth trading my freedom for health care. How do you feel about it? If my ass is hanging out there on the line, I want more than a BB gun for protection. Smitty

Hellbender
10-17-2003, 05:02 PM
Evan and Yankee1--I had no idea someone was building what I wanted. Looks like I just need to start saving a few pennies.....

Thanks for the info.

HB

debequem
10-17-2003, 05:03 PM
Max barrel length would be a function of barrel volume vs total gas volume at STP.

Once the pressure inside the barrel is equal to pressure outside the barrel, the projectile will no longer accelerate and theforce of friction inside the barrel will degrade projectile volicity.

Actually, the internal barrel pressure should be slightly higher than the external when teh projectile starts to exit since you need to overcome projectile friction.

That being said, that would be a mighty long barrel I would suppose. So, the answer is longer is better, but at some point it is going to be difficult to handle.

Evan
10-17-2003, 05:34 PM
Smitty,

DON'T get me started. Too late. The entire gun registration scheme is a total horrendously expensive fiasco. As the deadline approached (start of 2003) the gov kept revising downward the estimate of the numer of unregistered firearms in the citizen's hands. This was to make it look like the program was working since not very many people were registering. I even know a cop who had not registered his personal weapons shortly before the deadline.

What we now have is a LOT of people who "used" to own firearms here. Also a run on 6" sewer pipe with end caps and kitty litter dessicant.

The entire program is just an attempt to get votes from clueless bleeding heart liberal city dwelling whining tree hugger sympathizers who are afraid to sleep with the lights out.

bikenut
10-17-2003, 06:54 PM
Evan, I hear ya. Too bad these maniacs will end up running the show. They have a real good plan, if only all of us old neanderthal Vikings would get on board and stop messing up "progress". Makes me glad I'll be dead in 50 years, (maybe less) our Founding Fathers would be rolling in their graves right now if they knew what was going on.

lalatheman
10-17-2003, 08:46 PM
The whole project hinges on the gas release mechanism. . .

Seems ike a good starting point would to obtain an inexpensive co2 oe pump pellet gun and take the thing apart even sacrifically .
Dave

lalatheman
10-17-2003, 09:42 PM
Paintball gun release mechanisnm could be looked at too . My thought is that they are probably "slower" than say a pump pellet gun . All the guns I'v heard of used canned propellant use CO2 possibly because CO2 is a liquidat that pressure . Paintball guns use a standsrd cyl about 8 " by 2" diiameter I think.
I just put a pressure gage on a 20 pound CO2 fire extinguisher and measured 1150 pounds pressure, These are set up with standard 3/8 " NPT fittings.
I heard long ago that 30-06 rifle develops 50,000 lbs breech pressure on firing.
Have long wondered about a 2 stage piston / 2 pilot valve system to develop a breech pressure abone the gas tank pressure , like a hydraulic jack in reverse.
Have heard scuba tanks go up to 5,000 lbs .
My approach would be to not decide on a caliber ahead of time but to get the all important release mechanism and try it on as many bores and barrel lengths as possible,
What about those dudes that shoot pumpkins half a mile wirh long barrel cannons , I would guess they just use a simple manual ball valve. Thats the other end of the spectrum sounds like fun though .
Dave

Hellbender
10-18-2003, 12:31 AM
<font face="Verdana, Arial" size="2">Originally posted by lalatheman:
The whole project hinges on the gas release mechanism. . .

Seems ike a good starting point would to obtain an inexpensive co2 oe pump pellet gun and take the thing apart even sacrifically .
Dave</font>

Yes it does, and I would ideally need a discharge hole OUT of the air cylinder the same size as the barrel, which the paintball and normal air gun does not have (I've looked at both, they are very small)......

dnsbss
10-18-2003, 12:34 AM
Tony: I have been trying to figure out how to use propane and air with spark ignition for a high powered air rifle

Evan
10-18-2003, 01:09 AM
Dnsbss,

That wouldn't be an air rifle, that would be a firearm.

dnsbss
10-18-2003, 09:45 PM
Thats OK if its a firearm,I still need help designing it

Evan
10-18-2003, 10:10 PM
Use a peizo electric igniter from a barbeque lighter to fire the mixture. You will need compressed air and butane, a butane lighter could be adapted as a fuel source. A blowback valve of some sort, a combustion chamber, maybe a couple of cubic inches. I've thought about this myself. Get caught here with one and go to jail, do not pass go. Same with the rocket launcher I always wanted to build.

Jaymo
10-19-2003, 01:33 AM
Could a paintball gun be modified to perform as a smaller bore air gun? Replace the barrel with something around .44 cal.
Hmmm. I've got some 1/2" ID seamless tubing, a big CO2 bottle(like what's used for soft drinks), a ball valve.

I used to use a 1/4" ball valve and pipe nipple as an air blowgun for blowing ALL the dirt out of the radiators of forklifts during PMs. Worked much better than the store bought blow guns. They freeze up in cold weather. That sunny beach would launch the balls from junk bearings out to parts unknown.
What about a 3/4" valve pressurizing a 1/2" Bbl? Or maybe a 1/2" valve and a 3/8" Bbl. Seems it would work better than using same size valve and barrel.
Hmmm, 1" valve and 3/8" barrel. That should develop some velocity. Now for a breechblock design.

Evan
10-19-2003, 01:47 AM
The way to control the charge of air admitted to the barrel breech is with a shuttle valve. It is spring loaded (this could also be air) and when the trigger is pulled it slaps through the valve bore exposing the ports on either side of the bore to the through hole (not necessarily round) in the valve piston. Controlling the spring (or air) pressure controls the speed of the valve travel and therefore the charge. A second valve is needed to cut off the air when re-cocking.

Yankee1
10-19-2003, 02:17 AM
Hello All
The airgun has an hammer that is cocked
compressing a spring. When the trigger is
released the hammer strikes a poppet valve
that opens for a short duration of time
causing the released air or propellant to
flow into the chamber behind the pellet
moving it down the barrel.The hammer mentioned often is cylindrical and long in
shape with the spring at one end and the
portion that strikes the poppet on the other end. The trigger engages a notch in
the center of the hammer.
Regards Yankee1

Evan
10-19-2003, 04:28 AM
Yankee,

Are you talking about airguns powered by 2500 psi? A shuttle valve isn't affected by the pressure, a poppet valve becomes harder to open the higher the pressure is.

Samuel
10-19-2003, 06:34 AM
what about a spring piston air rifle?

I had a beeman when I was younger.... they seem to work well. I always wanted a larger size.. I think they make pellets to .25 will have to check tho

plink plink

Hellbender
10-19-2003, 06:19 PM
<font face="Verdana, Arial" size="2">Originally posted by Evan:
The way to control the charge of air admitted to the barrel breech is with a shuttle valve. It is spring loaded (this could also be air) and when the trigger is pulled it slaps through the valve bore exposing the ports on either side of the bore to the through hole (not necessarily round) in the valve piston. Controlling the spring (or air) pressure controls the speed of the valve travel and therefore the charge. A second valve is needed to cut off the air when re-cocking.</font>

Yes, this was what I was thinking also.....is there anything comercially available in the sizes (say a 3/8"-1/2" port)we would need that anyone has ever seen or heard about?

Yankee1-the valves you are thinking about are what is used in the CO2 guns (pellet and paintball)....correct?

I don't see a way to get one to work with the MUCH higher pressure and volume on a big gun and 2500 PSI. The hammer weight and spring pressure needed to open it would be very large, I would think; but I may very well be wrong.

Have you guys actually seen or shot one of these big airguns?

Thanks,
HB

Hellbender
10-19-2003, 06:24 PM
<font face="Verdana, Arial" size="2">Originally posted by Samuel:
what about a spring piston air rifle?

I had a beeman when I was younger.... they seem to work well. I always wanted a larger size.. I think they make pellets to .25 will have to check tho

plink plink

</font>

Samuel--the cocking force and spring recoil on a gun of this power would be prohibitive, I believe. You would have to eat a lot of Wheaties http://bbs.homeshopmachinist.net//biggrin.gif

Yankee1
10-19-2003, 06:25 PM
Hello Evan
Yes. My Anschutz 2002 CA uses 3000psi
and has a poppet system like I was describing.The hammer is the rebounding type.As the spring pressure is increased
the rebounding hammer holds the poppet open
for a longer duration causing more air to be released. There is also a spring that
closes the poppet valve.So we could describe
the poppet action as being bounced open for
a brief period of time. After the hammer strikes the poppet the poppet closing spring
closes it.My rifle has a pressure regulator
in it between the reservoir and the poppet
regulating the pressure to 1000psi.
yankee1

dnsbss
10-19-2003, 06:30 PM
Evan, that is just what I had in mind for a pistol type,not sure how to proceed.

Cass
10-19-2003, 09:00 PM
I was hoping to read something about spring powered air guns with ether injection. Anyone have information on the European 50 cal. ether injection guns? Easily kills deer.

Yankee1
10-19-2003, 11:42 PM
Hello HB
Yes they are used in paintball and Co2
and compressed air as well. There is no problem with 3000 psi and poppets opening.
The field target guns available on the market now shoot unregulated at 3000 psi.
The problem becomes variable points of impact as the pressure drops. They overcome
this by recharging at certain points of
pressure. They refer to the pressure range
that is most accurate as "The sweet spot".
These rifles are available in 9mm also.
Also available in .177,.22cal,20cal,25cal
and as you already know some people are
making them in 45cal and 50cal.With my
Anschutz type rifle we have contests shooting at targets with pictures of common
house flys on them, we are only permitted
head shots in order to score on them because
of the olympic type rifles we use.Yes they
are that accurate.
yankee1

Yankee1
10-19-2003, 11:52 PM
I forgot to mention the distance involved,
It is 66 feet or 22 yards. Its not too difficult indoor but when we shoot outdoor
wind maks it much tougher.
yankee1

IOWOLF
10-20-2003, 11:24 AM
i own several air rifles some are high power p.c.p from .17 cal. up to .50 cal. i enjoy them all, as for taking big game, not as of yet. but i regularly shoot grasshoppers at 50 yards,easily with my .25 cal career rifle.

andy_b
10-20-2003, 02:45 PM
i'm surprised no one mentioned Dennis Quackenbush:

http://ns.connext.net/~daq/index.html

andy b.

Jaymo
10-20-2003, 08:30 PM
Please excuse my ignorance, but, what does p.c.p. mean?

Evan
10-20-2003, 08:37 PM
PreCharged Pneumatics

Hellbender
10-21-2003, 11:42 AM
<font face="Verdana, Arial" size="2">Originally posted by IOWOLF:
i own several air rifles some are high power p.c.p from .17 cal. up to .50 cal. i enjoy them all, as for taking big game, not as of yet. but i regularly shoot grasshoppers at 50 yards,easily with my .25 cal career rifle. </font>

IOWOLF--On your big rifles (I have several standard spring-air, pump and CO2 guns up to .25 cal and paintball, so these questions only pertain to bigger stuff), do they all shoot round ball?

If so, are you using standard lead muzzleloading balls? If not, what ammo? Have you tried any discarding sabot (available for muzzleloaders)?

What kind of velocities do you get?

What is the bbl. made of? Is it fully rifled? Squeeze bore at the muzzle?

Is it a poppet valve release mechanism?

If so, how bad is the counter-recoil from the actuation spring/hammer? Or is it noticeable or affect accuracy?

How noisy is it?

Sorry for all the questions, but these rifles fascinate me.

Thanks,
HB



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