How a spring-piston airgun works

by B.B. Pelletier

Today I’m writing an emergency blog I shoehorned into the list. Sparkie, who assures me he is NOT Clark W. Griswold Jr. (Chevy Chase’s Christmas Vacation), sent me a comment with his interpretation of how a spring-piston airgun worked. He was off a little, as many people are, so today I will show you exactly how a spring-piston gun works.

The spring-piston airgun is the simplest type of powerplant from the standpoint of parts. There are but a few. It’s a wonder that it’s also one of the most recently developed, but read this report to see the history.

The gun works by the force of a piston compressing the air in front of it to power a pellet. A powerful spring or charge of compressed gas drives the piston when the gun fires. Besides a spring, in the past both dynamite and gunpowder have been used to power the piston. On the back page of the January 2009 edition of Popular mechanics, there’s a brief piece about a gas-powered gun NASA uses to test micrometeor impacts. That gun is powered by gunpowder that compresses hydrogen gas to 100,000 psi. That gun has no piston, so the sabotted projectile acts as the piston instead. Interesting!


No matter what type of spring-piston mechanism it is (breakbarrel, underlever or sidelever), the barrel aligns with an air transfer port like this when the gun fires. The air transfer port is shown at the right of the picture. These parts are in front of (to the left of) the compression tube shown below.

They all work the same
All spring-piston guns have a spring-powered piston (some have more than one) inside a compression chamber. That chamber connects to the barrel through an air transfer port. When the gun is cocked, the piston is withdrawn into the compression chamber, and air is drawn through the transfer port.


Inside the compression tube, the piston rests against the front of the compression chamber until the gun is cocked.

Here’s the secret!
This is what confuses a lot of people. Inside the compression tube, which is also called the spring tube, the piston rests at the end of the tube until the gun is cocked. The air transfer port is at the end of the compression tube and leads directly to the barrel. There’s no valve of any kind in this system. It’s like a soda straw that you can blow through to expel a paper ball. No valve is required.

When the piston’s withdrawn, it pulls air into a chamber that forms in front of it. That chamber is called the compression chamber. There’s nothing mechanical between the piston and the barrel, where the pellet sits.


When the piston is withdrawn upon cocking, a compression chamber forms in front of it. After that chamber lies the air transfer port and after that is the barrel.

When you load a pellet into the barrel, it forms an airtight seal. When the barrel is plugged with a pellet, the piston goes forward and compresses the air in front of it and the air presses hard on the pellet until it overcomes the pellet’s resistance. The pressure of the compressed air is high–above 1,200 psi in tests that have been done. But the AMOUNT of air at that pressure is very small–just what was in the compression chamber.

So, the pellet gets swatted on its tail by a tiny puff of air at very high pressure. The pellet cannot remain where it is, so it starts moving down the barrel. As it does, the air behind it loses pressure rapidly. After 8-10 inches, the air is almost at the same pressure as it is outside the gun. The pellet has accelerated to as fast as it will go by this point.

That’s all there is to it
There’s nothing more than that at work in a spring-piston airgun. There are different designs of powerplants, of course, but they all work by the same simple design. In a Whiscombe rifle, two pistons that are opposed come together like the clapping of hands, with the air transfer port at the center of where they meet. But the operation of the piston(s) doesn’t change.

Back in the 1960s, Jack Lewis, a noted gun writer and editor, saw a cross-section drawing of a spring-piston rifle and assumed that the blank space occupied by the air transfer port was a reed valve. He proceeded to describe the operation of that valve in great detail in his article about how a certain spring gun worked. The only problem was that THERE WAS NO VALVE!

What I am showing you here is all there is to this design.

Sparkie and anyone else who wants to learn more about how spring-piston guns work–here are two recommended posts. Both are multi-part reports.

The air transfer port

Spring gun tune

87 thoughts on “How a spring-piston airgun works

  1. Good Morning B.B., Such a simple eligent design. Thanks for the reminder. How are you feeling? Hope that your kidney is back to normal.


  2. Hi B.B.,A very interesting primer for all that are invovled in this sport.By the way in case she missed it,please tell Mrs. Gaylord that I responed to her message last night at about 10;00pm.Jersey Boy.






  3. B.B.,
    Thanks for a reminder on just how dirt simple springers (in theory) are. Your comment way back about how the “Cheap Tool Sale” $15 Chinese springers are “about as crude as they can be made and still function,” really stuck with me. I have one of those (B3, I think??) that I had to mash the receiver tube in a vise so that the trigger catch would stay latched into the notch in the sliding piston. Not too safe, really.

    I have experimented on a few different rifles with changing transfer ports, springs, piston weight, seals, etc, and have never been able to get more than about an 8% velocity increase, and probably as often, a velocity decrease. Do you think that given a specific cylinder volume and barrel length, most springers sold these days are pretty well optimized for max, or near max velocity? Seems like most can be tuned for better “shootability”, but trying to fiddle with velocity doesn’t yield anything too positive.

    Thanks,
    Lloyd


  4. Remember that a great deal of the velocity developed in springers comes from the dieseling or detonation of minute amounts of lubricant in the compression chamber. I loved the comment in the Airgun Bluebook that many Webley owners would purposely oil their Webley’s compression chambers to obtain greater velocities which is why many of them rattle when shaken. A local shop I go to refers to those fine Webleys as Wobblies.

    Ajvenom, that is a great website. I’ve referred many a burgeoning airgunner to that site to understand the mechanics not only of airguns but scopes, as well.


  5. BB, what am I missing? If I run the numbers, the swept volume of, say, a Gamo powerplant is around 3 cubic inches. When the pellet gets around 10" down the barrel, the volume behind it (assuming the piston is 'home' by this point) is only about 1/4 cubic inch. Seems to me that there still oughta be some significant pressure behind the pellet (>150psig), especially since the compression and expansion process happens so quickly it's probably close to being adiabatic. Certainly less than the 1200psi peak, but still much greater than the pressure outside the gun.

    Or did I forget something?



  6. Lloyd,

    One experiment I did on a Chinese springer by sleeving the transfer port to make it smaller and installing a Lothar Walther barrel netted me a gain of over 100 f.p.s. in a rifle that had been shooting in the high 400s. So that gain was greater than 8 percent, but I do support your observation that given a swept volume, the changes that can be made are not that dramatic. But changing the shooting characteristics is often all I want to do anyway.

    B.B.


  7. Vince,

    If he is correct about where the pellet is, then, yes, you are right. I believe the pellet waits longer to take off. Or stated differently, I believe the piston is within a few hundredths of an inch of the end of the chamber before the pellet starts to move. So the temperature is higher – it IS adiabatic – and the pressure is also higher.

    However, I don’t think either concept is correct all the time. I think every different model pellet produces a different acceleration time, and my model is just the ideal – not the norm.

    It sure makes for interesting conjecture.

    B.B.


  8. http://www.arld1.com/

    Here’s the main page. It has several other demos and even a link to that highly competative online store: AIRGUN EXPRESS aka AGE. LOL!!! (click on it and you’ll see why.) It was one of my favorite links. I still have it on my computer today for sentimental reasons.

    I do see a few people here around on other airgun forums and figured maybe perhaps I’m not the only one (see below). So for what’s it’s worth:

    Top Ten Signs That Indicate That You May Be an Airgun Addict:

    10. The potential dangers of a twenty dollar air rifle only adds to the thrill of shooting one.

    9. There are one or more items in your household with an unnecessary or unexplainable hole in it.

    8. You’ve spent more on an airgun accessory than you’ve spent on your spouse’s anniversary gift.

    7. You can actually recite an airgun formula and have actually figured out the ftlbs of an everyday object.

    6. You can’t go one day without thinking about airguns or saying any airgun related vocabulary.

    5. You have more links to airgun sites than all other links combined on your computer.

    4. You find you can improvise and make a target out of anything.

    3. You can talk about airguns for hours with complete strangers, who you will probably never meet again.

    2. You actually take pictures of your airgun(s) and share them with others.

    1. You believe there should be no limits on the airguns you can own and operate safely.

    I’m at 9.5, I haven’t shot a hole into anything that didn’t deserve it, but I did manage to carelessly put a dent one of my hvac ducts.



  9. ajvenom,

    Great link on the diagram!!

    I had to take trigger assembly out of my Air Arms S410 .22 cal, because I tried to adjust it, but made it worse. So I took it out, so I could see how it worked… And adjusted it out of the stock, where I could see the first and second stage work.
    If I had had that diagram, it would have been easy, without taking it out..

    You got me!! I’ve got the holes to prove it.. only a few from me though…

    Ouch!! that one about spending more on an air gun accessory than on my wife’s gift really hurts… cause it’s true!!

    But I always pretend that’s it’s a business….. so it’s OK…

    Wayne,
    Ashland Air Rifle Range


  10. Dear BB,

    As usual, excellent article on springers.

    Glad to hear you’re feeling better.

    FYI, based on your recommendation, I placed an order for the AirForce Diopter Rear Sight (for my 853C) last Friday.

    I was hoping that Santa will bring it for Christmas, but the “in stock” date moved to Dec. 22nd.

    Can’t wait to get my hands on it. I feel like an 8-yr old child waiting to open my presents. I guess some of us just refuse to grow up !

    Have a Merry Christmas !!

    Stingray



  11. Kevin,

    My guess is that no amount of intervention can help us now, so let’s just skip that part, and enjoy the ride…

    There is no going back, it’s a one way road.. just look at B.B.

    Wayne


  12. That woud be terrible……come home and to find all your friends, family members & peers sitting around waiting for you after all your airguns, ammo, tools and supplies have been thourghly removed from the premisis.

    I hope you doing better BB.

    Cool Fred, perhaps we should all get together and start a links page. Do know if the person who made that sight designed those demos?

    Usually I ask before a post a link in a major forum, but there was a note to post in any forum on the page. The email is for Perry Babin. Maybe BB/PA can get a current banner up there and have Perry as a guess blogger?

    Wayne, I almost called you when you sold your Disco, but I'll wait til you sell your AA410 or perhaps a TX200mkiii if you have one.



  13. LOL…BB I can’t remember the word you had for it…was searching the past blog for it.

    At least you seem pretty honest. Sometimes I have talked for nearly hours to sales people in firearms/sporting goods stores who are generally hooked on shooting too. Not once have I ever met one that has ever asked if I wanted to buy something or even look at anything. Usually the good ones are just happy to be working in the area that they like and know that you will eventually buy when the time is right.

    Sometimes I wonder why I like airguns so much. Perhaps because it’s such a cool sport or could it be the cool helpful people in the sport and forums. I like to think that it’s both.




  14. Ah, the simplicity of springers gets me every time. One of the real rewards is feeling the recoil of the mechanism resonate through the body.

    B.B., it sounds like the spring piston has to maintain an airtight seal as it moves back and forth which sounds like the trickiest design problem. Do they accomplish this by a very exact fitting of parts or is there some material like teflon involved?

    That’s astonishing that pellet acceleration is finished after 10 inches. No wonder you need to really watch the follow-through. This part of the design seems to cry out for enhancement. I guess the only two ways to do it are to put more air into the charge or somehow meter it so that it is applied longer, sort of like slower-burning powders in firearms, but I suppose that the compressibility of air is a major barrier. That was what stood in the way of my air powerlet invention.

    If shooters on a PCP and a springer can shoot equivalent groups, is it fair to say that the one on the springer will do better with firearms other things being equal?

    Matt61


  15. ‘You can’t spackle a couch’??? Really? One would think that you couldn’t sand a couch either.

    How on earth are you supposed to prep it for painting??? Or do you have to use Bondo or Tiger Hair?


  16. bb- I just stumbled upon a BSA lonestar but can not find jack about any of their guns. You mentioned one in yesterday’s report, have you had any experience with this particular rifle? What would you expect for accuracy?
    Also, I was thinking about getting a pump with my future pcp. About what is the maximum pounds of pressure to fill a tank to 3000psi with a hand pump,I hope not 3000 ;-).
    John from jersey


  17. Would it be an improvement to put on a valve anyway: this way the pellet will have air behind it and start moving before a certain pressure threshold is met to open the valve. It could mean higher efficiancy and energy transfer.



  18. Matt,

    The piston only has to seal going forward – hence the parachute design that inflates and widens as it catches the air.

    Material is a component and fit is another component.

    No spring gun shooter can hope to equal the accuracy of a PCP. While rifles like the TX200, Whiscombe and Diana 54 are amazing springers, a top PCP will do better. And follow-through isn’t nearly as important. This only really shows up at distance, though, so it is easy to be mislead.

    Matt, the air powerlet was invented and marketed a decade ago. It never worked.

    B.B.


  19. b.b.
    I know that firearms and pellet guns have a break in period, but do BB guns.
    I wouldn’t have thought so, but…
    Throughout the year the boys Red Ryder has consistently given the humourous ‘minute of popcan’ accuracy.
    All of a sudden, in the last few weeks, it has gotten downright accurate. Accurate being a relative term.
    After about 700 shots the thing all of sudden tightened its grouping. At 25 feet it has gone from a consistent 3-4″ grouping (5 shots), to easily 1.5 inches!
    CowBoyStar Dad


  20. Jersey John,

    A hand pump takes about 120-140 pounds of force to get to 3,000 psi.

    BSA Lonestar? I may have responded to it in passing. but I don’t know the gun.

    BSA has never been well-represented here in the USA. They have always allowed small distributors to represent them and they have had a low importation rate.

    They are great airguns, but the U.S. doesn’t know them very well.

    B.B.





  21. BB/CowboyStar Dad,

    That’s not uncanny accuracy for a Red Ryder in my experience — 2″ is pretty normal for both of mine, a 1938 and 1938B. The 1938 (circa 1977) is a bit more consistent, despite having been left cocked in a basement for several years (not by me:))…It probably has 50,000 BB’s through it at least (my misspent youth, plus parts of 4 brothers’), so it should be worn in:).


  22. Yeah, truthfully I was stunned.
    After an evening shooting I’ll often finish up with a few shots through the Red Ryder myself…it’s just fun.
    About two weeks ago was when I first noticed it. 5 shots all in an area that could be covered by a twoonie (a Canadian coin a little less than 1.5″).
    I figured it was just a fluke but I’ve tried it a number of times since and it keeps doing it. Tight groups and no flyers (which were common before).
    It’s kinda scary…a 7 year old with a BB gun that can actually hit what it’s aimed at ;-)
    CowBoyStar Dad





  23. ajvenon: What a great link. Thanks for sharing it with us.

    Help me please, family is on the way over. Sent #1 son link and was explaining how honeing, secret sauce, shot peening, sear polishing, and guide rod fitting would make the “gun” much smoother….gotta run now and hide my last rifle their cars are pulling up Mr B.


  24. Ive been thinking of adding a gas spring to my crosman quest 500. Does Anyone know if The gas springs sold on pyramyd air will fit in my crosman quest 500. (this is a Canadian version of the 1000 with a lower velocity)


  25. I’ve heard that some will fit a quest 1000. Also, may fit an 800 with some work. As for velocity they may be too much? But you came to the right place….I’m sure BB or someone at PA would have the answer.


  26. B.B.,

    I have a remmington summit 1000 and am managing 4 to 5 inch groups
    at 100 yards. The mainsprings are
    crap and break every few months. I have looked at other springs but I
    would really like to move to a gas ram. However I cannot find any that I am sure will fit and I want around the same velocity I have now (900 fps 10.5 grain pellet. If I am not mistaken my rifle has the same powerplant as the crosman quest 1000.

    So do you have any suggestions?
    -Dan


  27. Jersey John,

    The BSA Lonestar is a very powerful PCP. It only gets about 22 full power shots. It takes a 232 bar fill. From a 195 bar (about 2,800 lbs, that’s all my tank has now) fill, 10 shots with 21 gr. Kodiak….. hi 956fps, lo 913 avg. 938fps…
    It is very loud, like a 22 rim fire. I put a mod on mine and it’s pretty quiet now. It is very, very accurate, but only with the 21 gr. Kodiak. All the others less heavy, just go to fast to be accurate. It does OK with the 28 gr Eunjins, but they are not close to as good as the Kodiak.

    Very good balance, shoulders well. The cocking button on the end, under the air tube, is very nice for keeping the gun to your shoulder while you cock and reload. It has a nice large loading area for big cold fingers. It would make a good hunting gun.

    Wayne,
    Ashland Air Rifle Range




  28. B.B.

    Me, in “tune with springs”? I think you meant Vince or Dr. G..

    I just buy and shoot and talk nonsense..

    Were you typing fast, because you had to go pee?

    Wayne
    Ashland Air Rifle Range



  29. B.B.

    I hope it was OK to tease you about your kidney stones… since your getting better..
    Don’t forget to have a few brews.. I saw that one on the list of natural cures too.

    Wayne


  30. rule # 12
    You arrange for delivery of your airguns/accessories when the spouse is not home.

    #13
    Sometimes rule#12 is not possible so…You have designed and successfully executed a plan for getting/stashing your airguns/accessories before the delivery driver rings the doorbell. As a result, the spouse has no clue that you just received airguns or accessories. The success of your plan gives you a victory rush.

    –Davee1


  31. ajvenom,
    Like that website too. The scope demo’s are great. And you can print some fun targets.

    I have to admit to having holes in my wood fence and a few lead pellets must be pick up off the bottom of the swimming pool from time to time.

    Also have a hole in the drywall in my home office… shooting trap back blew out. Was a very low power gun though.

    Mr B.,
    Thank you too. Have seen that pellet guide before and didn’t book mark it. Nice to have.

    DB


  32. Top Ten Signs That Indicate That You May Be an Airgun Addict:

    I bet we can make it to 50 with less than 10 more comments…

    14; You dust your airguns more than your wife’s picture.

    15; There is no room in your closet for clothes.

    16; There is a pile of long empty cardboard boxes in the recycling.

    17; You would rather shoot than watch TV….even John Wayne

    18; You shoot while talking on the phone.

    19; You have a file with number of shots, fps, on more than 10 air guns.

    20; You spend hours and hours reading and writing on blogs.

    Can we do 50?… be honest now..

    Wayne
    Ashland Air Rifle Range


  33. 21. You’ve ever considered weighing or washing pellets.
    22. You’ve watched a TV show on how CO2 cartridges are made.
    23. You know and care about the difference between Arctic and Old School.
    24. You keep spare seals for each rifle you own.
    25. You can spend hours deriding WD40.
    26. You know the MOA’s distended by most common beverage and food containers at multiple ranges.
    27. You’ve planned a vacation to Ashland Oregon, although the family thinks they’re going to Disneyland.
    28. You’ve ever debated with yourself about the spacing on your mainspring.
    29. You’ve ever shot in a freezing gale.
    30. Your wife makes fun of your BB gun collection



  34. BG_Farmer,

    Now those are better than the first ten!!!

    I”ll add
    31. You spend so much time on the keyboard typing blog comments, that both your dogs come and knock both your hands off the keyboard at the same time.

    Wacky Wayne




  35. Dan,

    I replaced the stock spring from my Remington Summit with a Maccari spring. Looking at his current spring selection, I think I used the E3650. I recall that the spring guide in the Summit is 0.500″OD. I’m going by memory here as that was many airgun jobs ago. I’m positive that I also turned a new longer spring guide. Doing this will cure your spring failure problem. I probably also sleeved the inside of the piston with some sheet metal. I had some lock up problems with the gun. Took a few days to sort out. Poor hinge design on that gun.

    Not sure if the gas spring conversion will work. If not, the Maccari spring upgrade is a worthwhile addition for about $25 shipped in my opinion.

    Derrick



  36. 32. You need to take a shot in the morning before you can function normally.

    33. You are afraid to answer the question, “Would a normal person have this many airguns?”

    Lloyd



  37. BG_Farmer,

    When they get here they can ride the real mountain, Mt Ashland, for 20 miles down to the air rifle range.. skis in winter and mountain bikes in summer… pellet guns on back with field targets set up on the way..

    Bumper cars around the lumber mill.

    Pirates of the ponds rides in Wacky Waynes’ Wonderful Water Wagons.

    Alice in Wonderful Wacky Waynes’ World.

    And the most fun of all;; The Waziboy Teacups.

    Tell them it’s the newest version.. Walt’s spirit designed the place.

    Wayne



  38. #35 – You have a big tub of lead from expended pellets and you wonder how much it would cost to turn it all back into $0.02 pellets.

    #36 – You already have more than 5000 pellets.

    BB – Been busy – a lovely blog from your better half. A common trait of successful men is marrying up.

    FWIW – the inter-mounts for the 1377 work fine on the 717. (Q: Why would I mount a dot sight & laser on a gun with perfectly fine sights? A: Because I can.)


  39. B.B.,
    I aplogize in advance if you have already answered my post. I am unable to find the post.
    I recently had to send my rws panther model 34 back to rws for a mainspring replacement.
    I’ve shot about 30-40 pellets thru it and it keeps dieseling. Is this bad for my gun? what should I do?
    P.S. I read your post on dieseling, but it didn’t mention what to do.
    hegshen


  40. hegshen,

    Yes, I did answer this. I said that some dieseling is to be expected after work on a springer and that shooting is the best way to deal with it. Actually the gun always diesels and what you are experiencing is called detonation. You don’t want it, but after years of testing I have not found a better way of dealing with it than just shooting the rifle until it stops.

    So keep on shooting. You are almost through the break-in. Please tell me how it goes.

    B.B.


  41. Helow B.B.,
    My name is Adil Mashooq, I am From Pakistan. I like the the shooting hobby From the beginning of my teenage. I owned one air rifle Which was Made in Pakistan for $30. i used it for quite a long time. then i bought a Chinese made Air rifle for $65. Now i am Planing to buy a good rifle between $150-250. which could be used for Small game hunting as well as for target Practice. I have one riffle in mind for that purpose i.e. Walther Talon Magnum. it is .177 Caliber and also has much power for Successful Game Hunting. What would you suggest ??
    any other gun which i could buy instead of this walter talon magnum ??
    Or should i go with Walther Falcon Hunter Instead ??
    And one more Question !!
    We dun have a Big market for air-rifles here in Pakistan !!
    I am planing to visit Dubai next Month! So can i carry a air-rifle from dubai to Pakistan ??
    Is it allowed ??
    Are there any restrictions ??

    And yeah m looking only for the Spring-Piston Rifles !!!


  42. Adil,

    The Walther Talon Magnum is certainly a powerful hunting air rifle and would fit your needs. Another wonderful rifle that would suit you is the Diana 34 Panther. The Walther is more powerful and the Panther is more pleasant to shoot. Either one will kill small game.

    As far as travel restrictions are concerned, you need to contact the counties concerned. Every country has restrictions that are always changing, so it is impossible to keep up with them. You have to call before you travel. Don’t forget to check with Pakistan, too, as they may not only have restrictions but taxes. Some countries charge as much in taxes as the item costs.

    B.B.



  43. Adil,

    The Walther Talon Magnum is entirely unsuited to 10-meter competition. It would be like trying to race with a tractor!

    The Diana 34 Panther is also unsuited, but not as much as the Walther because it is easier to cock. But for 10-meter shooting you want a rifle that shoots under 600 f.p.s. – like an HW 25.

    B.B.


  44. But i am looking for a rifle under $250 which could do both the things i.e
    1. small game hunting
    2. Practice for participating in The competitions.[not actually participating] i ment to say that i will practice for that competition until i gather up enough money to buy anothe gun s[pecifically for the competitions.

    my monthly pocket-money is $20
    and i cannot affort 2 guns at a time !!

    In pakistan i saw Gamo Shadow 1000 for $225 that is Rs.17500 here it is too expensive to buy such guns !!









  45. Thanks fer the tutorial of great sage of compressed air. I had no idea of how the thingie worked, I was guessing!

    So on a multipump unit, you are mearly pulling the spring tighter each time?

    For more power in a given powerplant you either increase the air chamber size, (lungs), or make the spring much harder?

    On a Gun like Discovery, that you use co2 or 2,000 pounds compressed air, are there issues with water vapor and rust? When you compress the air if you don’t use a drier you have water vapor to deal with. I have compressor I am fixing and I opend the drain forgot it to find it piddled a huge puddle on my kitchen floor. I had forgotten about the water vapor.

    I am so confused with all the cool stuff I will stick with my blow gun, fer now. It is the only aerobic exerciseI get. I have had it since I was 15 , you got the tube a hundred plastic beads and few feet of wire. I ordered several thousand darts. As well as additional 3 units for friends. One insane friend perched on second floor balcony (sort of ), and pinned pidgeons to the park bench by his house. The distance from the house to the bench was maybe 120 or so feet, and the vertical drop was about 20-25 feet, perfect site lines, no trees interferring. All was fine until he wasn’t fast enough to get there before a little old lady came and sat next to three almost dead birds pinned to the bench, as she ran screaming for NYPD , my friend calmly plucked the pidgies off the bench and rubbed the area with a clean brick crushing the pin holes.

    Eventually his mom, not knowing what it was, used it as a termater stake in the garden, mangling it. Then there was the day he and another carried his plastic handfinished Luger replica (1:1) onto the street. Impossible to tell in your hand, let alone from the street in an unmarked car, NYPD was very very interested.

    On the idea of the aircylinder (airpiston/shock absorber). How long do they last. I replace 2 of them in 17 years in same car. When they let go you think you have been shot with a 22 maybe. And this may seem trivial, but I guarantee, you shoot that gun more times then I open my hatch back in a decade. The pistons cost 15-45 bucks. the bill is 150.

    This is a fabulous site. I may break down and get my kid a unit after Xmas. I will keep telling myself its for him. I really don’t want him using my blowgun, it is way more danerous as the percieved danger is way less. At 19 year old, from 20 feet I shot a dart just barely through a 3/4 inch plywood. (i practiced breathing exercises daily and ran and bicyled every place)

    Ah well, the day when I was skinny and had hair, errr on my head! chuckle

    pizza dough is calling, the oven hit 550degrees, perfection in carbo’s

    sparkie


  46. Sparkie,

    You mention a multipump unit. Most multi-pumps are pneumatics and have no mainspring to worry about. There is one spring rifle that takes multiple cocking strokes to cock and, yes, that one does compress the spring more with each cocking stroke. But you have to cock that one three times to get it to work, so each cocking stroke does not allow a different power level.

    Most multi-pump guns compress air with every pump stroke. No spring is involved in powering the pellet.

    There are water management issues with precharged pneumatics. Correct pump purging takes care of them.

    No, the relationship for power is more complex that just more air or a more powerful spring. Read this report to see what I mean:

    http://www.pyramydair.com/blog/2008/10/steel-dreams-part-2-building-more.html

    As for how long gas springs last – nobody knows. I have one that is still doing wqell after 10 years. If it ever fails, a rebvuild will make it like new again.

    The gas spring on the lid of my camper topper fails about every 3-4 years and is not rebuildable.

    B.B.


  47. Hi,
    Great seer of “sears”. I found the pyramid site while looking for a “wrist rocket” slingshot, then your blog by searching for how to make leather cylinder cups (seals). I figured there had to people who made them for projects and , like me , are not given to giving away a ludicrouse amount of money for darn little product. Your blog has been instrumental in me finally understanding a toy of my youth, and perhaps will buy another. All this info and the sheer volume of items to choose from is quite daunting. I think I want a variable power unit since I will need to set up a basement range , but be able to take out the rabbits that overran my yard as well as the dogs that crap on my lawn. (you wanna dog, leash’m and pick up after ‘m), in my back yard they are targets. I may use the blow gun, NOT THE DARTS, that would be fatal,just the beads, they hurt like a bee sting, few shots in the rear they won’t come back. A lower powered bb gun would be as good, I think. So I must let this idea ferment a while, so fer now I must return to the “toy” I am making.

    If I can get the gizmo working, I will send you a picture.

    Your various treatises mentioned dieseling. It is my guess that is your unit compresses the air so fast it combusts some of the lubricants present. My Old Daisy Fieldmaster dieseled, or had a little smoke after a few shots, but I always thought it was vaporised oil, was it actual “smoke”?

    After reading about my gun, I am glad to know that it was wear and tear on gun, not me that killed it. I treated it right, I kept it lightly oiled, and did not treat it carelessly. When you cocked it, you could cock one way they no one could pull it back. I understand it split the spring retraction, in two moves, so failure to pull it back meant no fire. 10 years or so ago dad asked, I told him dump it, didn’t think it was worth fixing. Perhaps I acted rashly.

    sparkie

    “Suffieciently advance technology is indistinguishable from magic” … A.C.Clarke



  48. HiHo Sir Pelletier, bringer of knowlege of compressed ether weapons,

    Ah yes BB, the price is not right, but the memmories they would have been preserved, then passed down.

    I am curious about the dieseling though, one day maybe you’ll get to it. If it is what I thought it was, then never ever ever use WD40 on your guns. That stuff has btu’s in it, woof. Plus it probably would melt the seals if they were not leather real fast. They will kill o-rings as well, depending on what type material they are.

    Also I saw either here or on another site that it is very dangerouse to repair these babies and you risk serious injury or death. How? I am not being an upstart here, just asking real question, since “sparkie” has been wiped off 5,000 amp panels and the like. So Sparkie wants to know, so Sparkie does not sputter out! We use hand and machine pumped hydraulic cutters/benders that if the spring a pin hole leak, can inject you like a Star Trek “hypo syringe”. Hydraulic fluid is quite toxic, and can kill you, on injection. Big toys can have big consequences.

    Well Time to put some cheese on the Chicken Parmesan and drop the pasta in the aqua salta.

    oh I fergit to ask last time, is there a way to email people from this or does one need to publish their email adress across the forum?

    ciao

    sparkie


  49. Hi B.B.

    I just googled dieseling and found on a site a whole discussion of it 2 years ago. It is as I expected and some people think it is cool other understand the dangerous part. WD40 is mention as a no no. You really should use the lubes made for the device.

    Do they ever have airgun shows here on Long Island? They are illegal in NYC , but, not in Nassau and Suffolk counties. Gotta go

    sparkie


  50. Sparkie,

    First things first. People trade emails here and then contact each other directly. To maintain some semblance of privacy they often use the older blogs for that, but I see all comments.

    Regarding dieseling, here is a 3-part report on it:

    http://www.pyramydair.com/blog/2007/05/what-does-dieseling-mean-part-3.html

    And here is another one-parter:

    http://www.pyramydair.com/blog/2006/01/do-all-spring-piston-airguns-diesel.html

    As far as repairing spring guns, the parts are sometimes under enough force to seriously injure you if they come apart in your hands. Here is a 13-part report on how the guns go together:

    http://www.pyramydair.com/blog/2006/08/spring-gun-tune-part-13-range-testing.html

    I have done lots on this topic, but this is the place to begin.

    B.B.


  51. Sparkie,

    The closest all-airgun shows to NYC are Baldwinsville, NY in July. That’s a suburb of Syracuse. The next closest is a combined Firearm/airgun show in Frederick, Maryland. It was held in October this year.

    Roanoke, Virginia, in the begining of November is the largest airgun show in the world. People fly in from Hawaii and Europe to attend.

    Davis Schwesinger, the former owner of Air Rifle Headquarters, does combined firearm/airgun shows on Long Island several times a year. He brings airguns and I think one or two others have tables therte, too. Google him.

    The Connecticut show will be held in 2009. Bug me and I’ll try to get you contact info.

    B.B.


  52. Hi BB.

    I did google him and sent an email that I think will get to him. Ct is closer then syracuse, although I have a friend up there who is an avid sandbag shooter. He is the gent who told me of WD40 and its having more power to it then regular oil, when burned.

    sparkie


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