Some air rifles ARE firearms??

[Oldnamvet]

A quote from part of an article on air rifles. I never knew that. Guess you are never too old to find out new stuff.
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Why is timing so important? Well... sporting spring airguns burn oil!!!! They are oil burners. Oil will combust in a spring airgun.

This "combustion" behavior of sporting spring airguns is very well documented in the book: "The Airgun from Trigger to Target" by G .V. Cardew and G. M. Cardew, and makes most thought provoking and entertaining reading. Their experiments revealed that up to 45% of the energy yielded in a test gun was derived from combusting oils.

If you have a sporting spring gun, you should notice a slight burnt oil odor just after firing a pellet; or if you can safely look down the bore from the breech of the opened gun, a slight golden haze will usually be seen. Such are evidence of the traces of oil that have been burnt. (A very little oil is necessary for proper combustion. It is usually provided by the piston head wicking traces of oil or grease thrown from the spring in the air chamber behind the piston. NEVER inject any oil into the air chamber in front of the piston unless specifically advised to by the manufacturer (not to be confused with the distributor!!))

"Sporting" spring airguns need to combust. "Match" spring guns generally do not. Match air rifles usually yield less than 6 foot pounds of muzzle energy. Adult sporting spring rifles are intended to yield just under the UK FAC 12 foot pound limit, or non-FAC guns generally in the 20 to 30 foot pound class. They all burn oil. Sporting spring guns are tuned for power; Match guns are not. Match spring guns generally work in the "pop gun" phase (re: Cardew) and are not designed to burn any oil whatsoever. That is why Match guns often use steel piston rings that exclude oil from the air chamber.

 

[RecoilRob]

Correct! Most call it Dieseling and it generally isn't a desireable thing as it isn't consistant and can cause velocity variation that throws off accuracy.

I've often wondered if the skirt could be filled with something combustable that could add some consistant energy to the pellet.

But, pellets aren't very aerodynamic and driving them supersonic doesn't work out too well as they shed velocity rapidly and come back through the Mach on their way to the target if it is very far away.

 

[pcf]

My Beeman Kodiak's and R-1s' owners manuals warn against using any lubrication on the mainspring or combustion chamber to avoid dieseling, only need to use oil for the occasional tuneup when the squeaking gets really bad. The Kodiak was sent in for a tuneup around 100K pellets. The R-1s have many more pellets through them and have never need any internal lubrication. Unless a drop of oil at the factory can last hundreds and thousands pellets and the more than 14 years..........

If you can smell burning oil in an air rifle, you're doing something very wrong.

Air rifles need compressed AIR to work. There ability to function without combustible material is exactly why they are not classified as FIREarms.

 

[Chawbaccer]

Oh, the joys of the day I discovered my Daisy would spit fire. I would squirt a few drops down the muzzle, dry fire a few shots and then drop in a BB. At dusk or even in the dark you could definately see a bit of fire coming out the bore.

 

[shermacman]

I still don't believe it. The temperature and pressure needed for Dieseling is way too high to be present in an air gun. And the ratio of fuel to air is too critically narrow to be randomly achieved.

 

[Jim Watson]

Believe it, it happens.
Weirauch made a spring piston air rifle built to diesel on purpose. The Barracuda, advertised in Shooters' Bibles of the 1960s. It had a chamber alongside the receiver that you broke a little ampoule of ether into. Cocking the gun sucked some ether vapor into the cylinder and when fired, it dieseled in a controlled and intended fashion. I think they claimed about 1300 fps with ether, well under 1000 without.

 

[mndfusion]

our breakbrl spring power Daisy powerline 1100 will give off a nice crack like a .22 if I put a little oil around the seal.

 

[MD_Willington]

dub-40 would do this in my .177... POW

 

[AJAX22]

I have an old sixtys book on airguns, the either injector was no joke, they claimed it could bring down small game at limited range. I'll have to read back up on it but I believe it was an aftermarket unit that could be bolted onto any sidelever with a small modification.

I've never actually seen a real unit, they must be unbelievably rare. Anyone have any experiance with them?

 

[cpileri]

voere

the voere daisy caseless was both.
it generated so much heat when its piston actuated that it could ignite the propellant in its special caseless ammo: it looked like a 22 cal LRN with a column of yellow powder stuck to it at the base.

If I ever find one of those rifles at a good price...
C-

 

[Funkytime]

Falcon Pneumatic

I've got an air rifle on my FAC that knocks out 30 ft lbs of energy at the muzzle. Great for bunnies in the garden or where the noise of a rim fire might disturb the neighbours.

Officer Dibble doesn't like me having it!

 

[Car Knocker]

pcf,

For your edification:

The Firearms (Dangerous Air Weapons) Rules 1969 require that certain air weapons can only be held legally on a firearm certificate. It is possible to measure the velocity of pellets, discharged from an air weapon, by the use of an electronic chronograph. From these measurements the kinetic energy of the pellet at the muzzle can be calculated. Air weapons deemed specially dangerous have a muzzle energy in excess of:

In the case of an air pistol: 6 ft/lbs
In the case of an air weapon other than an air pistol: 12 ft/lbs

Such weapons are classified as Section 1 firearms and are required to be held on a firearm certificate. These weapons are subject to all the controls and regulations pertaining to Section 1 firearms, although the "ammunition" (pellets) are not.

http://www.met.police.uk/firearms-enquiries/airguns1.htm

I believe some jurisdictions in the US classify airguns as firearms because they use an expanding gas to propell a projectile, as do actual powfer-actuated firearms.

 

[candr44]

Shermacman, you need a minimum of 16:1 compression ratio to have a diesel and if there is anything flamable in there it will burn. That is why carburated gasoline engines never got much more than 12:1 compression. I have seen diesel engine training films where a piece of wood is put in a glass tube with a glass piston then rapidly compressed by hand and set on fire. It was a tool used by soldiers to start a fire.

I would like to know where these diesel guns are found. I have never seen one. It sounds interesting though.

 

[colt.45]

"I still don't believe it. The temperature and pressure needed for Dieseling is way too high to be present in an air gun. And the ratio of fuel to air is too critically narrow to be randomly achieved." -schermacman

actually a 100psi pressure wave is more than enough to ignite oils.

 

[Sactown]

I bought a Weihrauch HW50 a month ago and the first time I fired it I smelled something burning. Couldn't figure it out because it was coming form the airgun. Looked online and read about Dieseling. I only smelled somethng burning the first couple of times I fired it out of the box. Don't smell anything now. I'm thinking it might have been some residual oil since the airgun was new.

 

[ATAShooter]

Virginia classifies a bb gun as a firearm. We had a local shooting over a bb gun about...I think a year ago. That's when I found out. Until then I didn't know that.

 

[ribbonstone]

Last seen being sold new in the 1860's-1970's, there was an HW 35 air rifle with an ether injector (the "Barracuda"). Wasn't the best design, and finding ether isn't all that easy, but the idea was that you injected a little burst of eather into the compression chamber...which would ignite as the piston compressed...and gain serious high velocity (and by combustion, could be though as a firearm).

Can still find them on some collectable air rifle sites...but it really wasn't a wise design. Blew seals with some regularity and injecting eather is a great way to strip all lubrication from the cylinder. Was also noted for occasionally setting itself on fire from the leaking ether.

Some locations do class airguns as falling under the same rules as firearms...might notice on some web-sites there is a list of places they will not ship an airgun to.

 

[JohnKSa]

Cardew proved that the higher-powered spring-piston airguns (most sporters) diesel a TINY bit (burning a miniscule amount of oil/lubricant with each shot) in order to achieve their power levels.

This was proved by firing a sporter airgun in an air environment and then in a nitrogen environment (pure nitrogen does not support combustion) and comparing the results. The results showed that the projectile energy was decreased by approximately 55%. The velocity was reduced from 636fps with a 14.4 grain .22 pellet to 426fps with the same gun and pellet.

"Full-scale" dieseling (or detonation as Cardew calls it) is also possible when too much lube gets into (or is injected into) the compression chamber, but that's an undesirable condition that can easily result in damage to the airgun and possibly even injury to the shooter.

Pressure in the compression chamber of a sporter spring-piston airgun typically exceeds 1,200psi with temperatures approaching 900C (1100F). The duration of these extreme conditions is extremely short. It is, in fact, the very short duration that pushes the numbers higher. The compression takes place so rapidly that there is no time for the heat generated by the compression to escape. Since the heat can't escape, it causes the pressure to rise far higher than the movement of the piston alone could cause.