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Education / Training Airsoft primer: Part 3

Airsoft primer: Part 3

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1
Part 2

This report covers:

• The spring-piston powerplant
• How an AEG works
• Upgrading an AEG
• The problems with upgrading
• How to upgrade safely

When we last looked at airsoft upgrades, we talked about how the tuner has to look at the gun as a system. Improving one part of the gun without regard to the others usually won’t make much of a difference. In some cases, it may even make the gun prone to fail much faster. I told you about barrels and gearboxes last time. Today, we’ll look at the powerplant, itself.

The powerplants of spring-powered airsoft guns are identical to the powerplants of spring-powered pellet guns. They have a piston, a mainspring and a compression chamber. The piston has a seal that’s most often just an o-ring. That’s no different than the BSA Meteor Mark IV I’ve been reviewing for you.

The big difference is that airsoft powerplant parts are most often made of tough plastic instead of metal. And the coiled steel mainsprings found in airsoft guns are wimpy compared to the springs found in pellet guns.

Airsoft piston and mainspring
Here’s an AEG airsoft piston with its mainspring. Note that this piston is made of nylon. Also note the piston’s final gear tooth is made of steel.

Compare springs
Compare a stock AEG mainspring (bottom) to an upgraded spring (middle) to a middleweight pellet rifle mainspring (top). Airsoft powerplants are weak, compared to pellet gun powerplants.

But they work! And they can be upgraded. You can install a heavier mainspring and a piston that fits the compression chamber tighter. These will boost your muzzle velocity. With some upgrades, it’s possible to boost the output so high that you have to use a heavier airsoft BB (plastic ball) to keep the gun shooting accurately.

We overlook what too much power does to our pellet guns, but it’s hard to ignore it when all your airsoft BBs are curving hard to the left, no matter how much you adjust the Hop Up! They go so slow and are so visible that you pay attention to them — like tracers in the nighttime sky — especially when you’re shooting a stream of shots on full-auto. So, you switch to the heavier BBs and find they’re even more accurate in that tight barrel you just installed.

My point is this — you upgraded your guns to get more velocity, but when you got it you lost accuracy. You had to switch to heavier ammunition to do what? Lower the velocity, again! Is that crazy or what?

Upgrading an AEG
While any type of airsoft powerplant can be upgraded, the most common type by far that people upgrade is the automatic electronic gun, or AEG. An AEG is a spring-piston gun that has a small high-torque motor to cock the piston. Because it’s electronic, a switch can be turned to make the motor operate just one time with every pull of the trigger — giving you semiautomatic fire — or to keep cocking and releasing the piston as long as the trigger is held down, which gives full-auto fire.

Unlike a firearm, the gun is not powered by the ammunition. It runs on electricity that powers a motor. As long as there’s juice in the battery, the action will cycle without regard to the presence of ammunition.

How an AEG works
The AEG has a large gear wheel that meshes with the piston. As the gear wheel turns, it draws the piston back until it reaches the spot on the wheel where there are no gear teeth. The wheel keeps turning; but when the teeth no longer hold the piston, the mainspring pushes it forward, firing the gun. The wheel continues to turn to the point that the gear teeth re-engage the teeth on the piston’s gear rack once again. The cycle repeats itself.

cocking gear 1
The AEG cocking gear is about to engage the first tooth on the piston gear rack. (Next photo shows this in detail)

cocking gear 2
The first tooth on the cocking gear is about to mesh with the first tooth on the nylon piston.

cocking gear 3
Here the gear wheel has rotated through all its teeth. The last gear tooth on the cocking gear has engaged the final steel tooth on the nylon piston. The cocking gear continues to rotate, and the piston will clear the gear teeth and be pushed forward.

cocking gear 4
Now the piston has fired and the gear wheel has rotated to the starting engagement position again. This keeps on going as long as the trigger is held down when the gun is in the full-auto mode.

For semiautomatic fire, the gear wheel turns only to the point of releasing the piston one time. It will rotate round to re-engage the piston gear teeth but not rotate farther until the trigger is pulled again.

If you install a stronger mainspring and better piston and compression chamber in your M4 AEG, that wimpy 8.4-volt battery that came with the gun will probably not run it too well. The gun that used to fire 700 shots per minute now struggles to put 400 out in the same timeframe, and everything sounds over-stressed — which it is. You need a stronger motor to power that new setup and a stronger battery to run it. And, while you’re at it, better get a battery with a higher mAH (milliampere-hour) rating. That way your gun won’t run out of juice after just the first magazine.

But you don’t just get a bigger battery. Sometimes, there’s no room inside the gun to house a bigger battery, and other times the bigger battery will take too long to charge when it runs down. Perhaps, it’s also time to change battery technologies from NiCad to lithium-ion (Li-ion or LIB).

Upgrading the batteries and motor
I did a two-part article on airsoft batteries for Pyramyd AIR back in 2008 and 2009. Here are the links: Battery basics –Part 1 and Battery basics — Part 2. Those articles were well-researched, and the information still holds true today. Maybe there have been some technical improvements, but batteries are still batteries.

I think you need to understand why you want a better battery. Sure, it’s for more power and so you can operate longer and recharge faster, but the battery does nothing by itself. It powers the motor that drives the powerplant. If you’re not upgrading that as well, you gain very little by just swapping batteries. Maybe you just get the gun to operate as well as you thought it would when you bought it.

It turns back on itself
So, you upgrade the motor, battery, compression chamber, piston and mainspring. Let’s say you even changed the gears from nylon to metal. Bully for you! However, as you shoot your new, more powerful gun, you notice the cyclic rate starts slowing down, again, after the first few thousand shots. This is exasperating because you’ve now doubled the cost of the gun by adding all these upgrades — not to mention hours of your time spent installing them and getting them to run right.

You tear down the gun, again, and discover that the holes in the metal gearbox that serve as anchors for the pins that the new steel gears run on are all enlarged. They’re no longer round but are becoming oval. The pins have loosened! That’s because either the gearbox itself (the housing that holds the gears) is too soft to take the strain of the upgrades you’ve installed, or you didn’t shim each new gear properly — and they’re slipping sideways as they operate. This puts undue strain on their axels (the pins). You have to figure out what it is and then either buy a replacement gearbox, or buy an upgraded gearbox (if one exists) or, most expensive of all, drill out all the pin holes in the existing gearbox and install steel bushings for the pins to rest in.

Is it really that bad?
Is upgrading an AEG airsoft gun really fraught with all these pitfalls? Not usually. If you proceed with caution and learn as you go, none of these things ever needs to happen, or maybe one will happen and you’ll be able to deal with it. The guy who suffers them all at the same time is the guy who just throws money at his gun without bothering to understand how it works in the first place.

How to proceed?
How should you proceed if you really want to upgrade your gun? Well, first I think you need to have a reasonable expectation of what can be done to the gun and why you want to do that. I remember watching an upgrade to a bolt-action sniper rifle a number of years ago. The owner wanted the absolute best of everything, so he went for the tightest barrel, the best piston and compression chamber and the strongest mainspring. Then, when he cocked his newly upgraded rifle for the first time, it suddenly dawned on him that the bolt that used to take 20 lbs. of effort to cock now took almost 40 lbs.! That gun was the baddest beast around, only nobody could cock it! Try cocking a bolt-action rifle that takes 39 lbs. of force some time if you don’t believe me.

Had this guy bothered to first research his project, he would have found this out before investing all that time and money. What he wanted was a bragging-rights sniper rifle with no thought of how to actually use the gun. How do you brag about a gun that nobody can cock? A good sniper rifle is accurate and not that difficult to cock. You don’t do it all with a heavier mainspring!

Allow me to make a comparison in the automotive world. You can buy a nice used Acura Integra and drive it daily, or you can lose your mind and mod the engine up to 1,000 horsepower. At that point (actually, long before you get to that point), the Integra is no longer suited for making runs to the mall. It’s sole purpose is to travel 1/4 mile in the least amount of time.

You can build an airsoft gun that launches 0.28-gram BBs at 550 f.p.s., if you want to. Just don’t expect to use it for anything beyond wowing your buddies at the chronograph. You left the real world of airsoft some time back.

A safer way to proceed would be to use kits that manufacturers put together for specific purposes. Read what users of these kits say about them before taking the plunge. Maybe, if the upgraded barrel you selected wasn’t so tight, you might get by with a lower-powered mainspring that was still an upgrade over your factory gun.

And maybe stop and take a moment to ask yourself why you feel the need to upgrade your gun at all. All airsoft guns do not need to be upgraded — just as all pellet guns do not need to be tuned right out of the box.

Another safe thing you can do is to upgrade a battery by one increment of voltage. It’s usually safe to go from an 8.4-volt battery to a 9.6-volt battery — especially if the gun you’re upgrading comes with metal gears. And you can upgrade the amount of battery storage capacity (mAH) without suffering anything except a possible space issue. A battery with a higher mAH rating is usually larger. On some guns like the M4s with the extendable stocks the batteries have to fit inside the forearm, so make sure there’s ample room before you buy the larger battery.

I could go on and on with this and that tweak, but I think you get the idea. Know what you hope to achieve before you break the bank trying for that last f.p.s.

138 thoughts on “Airsoft primer: Part 3”

  1. BB
    If the air soft guns use c sized nickel cadmium batteries recharging them should not take any more than 19 to 15 minutes max, I the world of RC car Racing I used to run 6 cell sanyo c cell battery pack and charge a 6 cell battery in 10 minute with a special charger that monitors the battery voltage and milliamp stored while charging, We would pump 15 amp into them and have a fully charged battery. It is amazing that they held up to that when the charging recommendation from Sanyo is 1200 milliamps for 12 hours, but we charged them in ten minutes.

    • buldawg
      Have you looked at the new LiPoly packs.

      That’s what we use with our 3D aerobatic R/C planes. You can get a bigger mah battery in a smaller package. So that means we get a longer flight time with less weight. And less weight in a aerobatic plane means more performance.

      And what I like about LiPoly’s is they don’t have the charge and dis-charge memory problem like the nicads have.

      • Gunfun
        I thought I sent you a reply but don’t see in this blog so I doing it again. Lipos are definitely better in terms of voltage and amp outputs and don’t the memory issues of Nicads but they have there own disadvantages also. Lipos can not tolerate being discharged below a certain voltage limit depending on the pack cell configuration so there would have to be a voltage cutoff limit circuitry in the gun to prevent from over discharge of the pack. I don’t know if that technology has been adapted to airsoft guns yet. I do have a friend that tunes and mods his airsoft guns and has installed I chip in his guns to be able to use Lipos but he also races cars so is aware of the need for battery voltage protection with Lipos. In the review that BB did he has not mentioned the use of Lipos only Nicads so I am unsure if there are guns that use Lipos, Maybe BB can shed some light on that. I do know that Nicads can have issues with memory retention, but that can also be reversed with a good quality charger like the Hitec Charger that I use on mine. It can charge then with any preset voltage or amperage rating, can cycle from full charge to full discharge with preset limits for any number of cycles all set by you , so you can break the memory issue with 5 or 10 charge/discharge cycles. I know when I used to race when I got done with each heat race and then the main my packs would be hooked up to a auto halogen light bulb and be completely discharged every time so they did not develop any memory issues. When I stored my pack for 20+ years when I quit racing I discharged them fully with my Hitec charger and then hooked them up to the light bulb and allowed them to stay on it till it would not even glow the slightest bit and then let them rest over night and repeat the process two more times and when I unpacked all my RC stuff a year ago and used my charger to cycle the batteries ten times they came back to 90% or more of the milli amp number that was wrote on the packs 20 years ago. So yes Lipos are much better, but Nicads if used properly can last for many years as well and charging times are not a factor with chargers like The Hitec because I would charge my 6 cell packs to full charge in ten minute by pumping 15 amps into them with the charger monitoring there peak voltage and shutting off right at the peak before the pack would be destroyed.

        • buldawg76 after I read your post it made me think off this.

          The electric R/C planes have something built into the speed controllers that allows a safe amount of voltage left to still be able to control the plane and have some power left to land. There is not a separate battery pack for the receiver. I guess they use the BEC (battery eliminating circuitry) on the cars now don’t they? I haven’t done electric cars in forever.

          But what the speed controller does on the plane. Well the type of speed controllers I have anyway. I set them up so the motor has the soft cut when the power gets low. With it set that way the motor will spin at only half power and then cut off completely after about 30 seconds of run time. Or I can program it so the motor will stop spinning immediately. Either way that I program the speed controller it allows enough voltage to power the servos so you can still have control of the plane. The speed controllers have a programing card that comes with the speed controller or you can buy them separately. The big trick to flying the planes is to have your transmitter set so a alarm will go off at a set time so you land the plane before the battery gets low voltage and make the motor cut start happening. I have a one of the transmitter’s that has the computer screen so you can mix the servos to operate 2 flying surfaces at once. And you can program in the percentage of movement you want and how much throw you get plus you can make the flying surface like the elevator move progressively faster as it moves more. That keeps the plane easy to control when you are flying at the center of your sticks and flying around normal. Put the farther you move from center the quicker the surface will move for like aerobatic flying.

          I have the chargers that will discharge each cell separately and then start the charge cycle. The LiPolys I use have 2 connectors on them. One for the speed controller and then another one that is used for charging. When the charger is done it will display how much voltage each cell has in it. And I also got a little device about the size of a quarter that I can plug in to the battery while it is still in the plane (the connector that I use to charge the battery). It will give me a digital display of how much voltage is left in each cell. That is my favorite little tool when I’m out flying.

          I think if a person did some research on LiPolys and took a look at some R/C catalogs it would be easy to adapt the battery’s and chargers over to the electric airsoft guns and even the air guns that use electric power to cycle the guns.

          • Gunfun
            The RC cars newer speed controllers that are for use with brushless motors have a built in low battery cut of circuit that shut the speed controller down when the Lipo battery gets to its threshold to prevent damage to battery. I did not think about a plane needing to have some backup power to allow time to land with that is not a issue with cars. You can buy a very small micro chip with a lead coming off it that will plug into the BEC port on older speed controls that protects the Lipo from over discharge. I still run my old Novak and Tekin controllers with brushed motors on Lipos and use the micro chip battery protector and it works good. I don’t know if airsoft gun have any sort of controller to limit or control power to the motors they use but I have a friend that is into airsoft pretty heavy and he said that he uses a similar chip to use Lipos in his guns. Yea it was quite a experience to watch all the space mission get launched growing up. I was standing out back of the GM dealer on Jan 28 1986 when the space shuttle challenger was launched and from watching all the previous launches We all knew instantly that something had gone horribly wrong when you see three con trails instead of just one. It was below 59 degrees that day and the launch had been delayed 5 time already for different reasons and NASA was bound and determined to launch that day even though the Morton Thycol engineers said it was to cold and the ice that had formed on the solid rocket boosters from the freezing temp the night before had not fully melted from the o-ring seals on the three stages of the boosters. So when it was launched and the burning solid rocket propellant reached the first o-ring seal of the joint between the booster sections that had been expanded from the ice build up in the joint the o-ring got burned up and allowed the flame from the solid propellant to act like a blow torch pointed directly at the large liquid hydrogen tank and when it burned a hole thru that tank you can figure out the rest as in KABOOM. We stood there in utter shock as you could see the 5 or6 pieces of what was left of the shuttle and engines fell back into the ocean. The astronauts area of the shuttle did not get that badly damaged in the explosion and they were most likely still alive as they fell back into the ocean. the news said that the impact with the ocean most likely killed them but we will really never know as they could have survived and possibly drowned instead as the shuttle was not designed to be a submarine. So it was great to watch all the rockets go up but it was also depressing when stuff went wrong.
            Still a lot of good memories

            • buldawg76
              I remember seeing the space shuttle explode when they showed it on tv. I cant imagine what it would be like to see it in person. That was definitely a sad day.

              And that’s what is always in my mind. Something is done over and over every day with no problem then all it takes is one little mistake and a disaster awaits.

              • the Challenger disaster is the subject I chose to do my 1000 word Senior term paper on. Talk about work!
                My hat is off to B.B. and anyone else who can devote the kind of effort it takes to be able to pick a subject and transcribe their thoughts , questions and speculate in an informative and inoffensive enough way to keep someone’s attention for so long deserves much respect. unfortunately in my case the available information was almost Zero and I ended up having to get very creative to be able to fluff it up to meet the 1000 word minimum in the 60 days allotted for full completion so I lost a full letter grade for turning it in too late! Still gotta B-!



  2. My point is this — you upgraded your guns to get more velocity, but when you got it you lost accuracy. You had to switch to heavier ammunition to do what? Lower the velocity, again! Is that crazy or what? …..
    I don’t think its that crazy, you got a heavier bb to fly as fast as light ones, more energy. More stability, but I hear what you mean if its just for the chrony, the gun actually functioning means the same velocity. Those airsofts van be very accurate, and I think .20g bbs are the lightest you can be accurate with unless the guns shooting under/around 300fps. The jump from .12 to .20 makes a huge difference.
    Can all the powerplant parts be made to pellet gun specs? With a power ful enough motor of course, ? Why don’t you see just ridiculous high power airsofts, like 700/800+?

      • That’s true, but who’d ever thought a .177 would be reaching 1500fps? Or the Rogue, out hunting African big game with an air gun? People always want the next craziness, but I think I was also asking what Mike did below- could this simple system be made to pellet gun specs or are the springs just never going to get compressed by any reasonible sized motor?

        • RDNA,

          It isn’t about the chrony for most “airsofters.” It IS about stability, or perhaps more specifically, the lesser effect of wind on a .43 gram “BB” than on a .20 gram one.

          So, accuracy and range are increased if an airsoft gun can shoot a .43 gram “BB” at 500 fps instead of shooting a .20 gram “BB” at 500 fps.

          There is another factor, and this is the most important one of them all to most airsofters: pain. Airsofters shoot at other airsofters, and they want their shots to cause pain, bruises, and welts on the friends they shoot.

          Try this. Go to the web page of any airsoft spring sniper rifle offered by Pyramyd AIR that has a LOT of user reviews. Open up all of the reviews, go to “Find” on your browser’s toolbar, and type in “hurt.” See just how many times a sniper rifle has positive comments such as, “Cool gun, it really hurts!” “Awesome rifle. It left a huge welt on my brother’s arm and he was hurting for days.”

          Airsoft guns are for shooting at people who also have airsoft guns and are shooting at people. War games / live role-play.


          • Michael
            I remember back in my early teens before airsoft guns we would have war games with bb guns just like airsofters do now because we did not have airsoft guns to use and yes the pain factor was a real important issue to us also. That’s why I bought the most powerful CO2 bb repeater pistol crosman made then, I think it shot like 500 or 550fps and would definitely leave welt on my buddies. We had no padding or protective gear either so we had a standing rule of no shots above mid chest area and no close range attacks you had to be at least 25 feet away to do battle out on the islands of Cocoa Beach FL. Its a wonder we didn’t shoot our eye out.

        • RDNA, I would like to think that would be dependent on the ingenuity of the designer(s) and materials or laws(both legal and physical) they had to work with or around.


    • RDNA
      You asked about if you heard of heavy pellets going faster than lighter pellets and I forgot to respond.

      Here is a .177 cal. pellet that goes faster than lighter pellets in every gun I shot them in.
      JSB exact heavy diabolo pellets.

      Look at the shape of the pellet also.

      • I noticed the skirt, its the same as the monsters, the base is delayed. Must be a center of mass advantage, or some minute change in the air flow, this is the kinda stuff that makes me love the science of airgunning, such subtle changes just multiply and multiply. Have you tried the HN rabbit magnum II? Or round balls? Investigating pellet shapes, the cool stuff to learn about your airguns literally never ends.

        • RDNA
          I haven’t tryed the rabbit magnums. But I have tryed round lead balls in some of my guns. To me they shoot ok for plinking. But they seem to not group as well as pellets the farther out you shoot. Again that is what I have seen. Maybe other people have taken more time with the round lead balls and had good results.

          You just never know what your gun may like you know. And yes that’s what I like about air gunning also.

          • So I went out to do some distance shooting, find out my limit with this NP. Problem is I need a portable benchrest. The places I have to shoot are all out in the woods, and at home I only have 20 feet. The tripod wasn’t very good, when I just went out I was prone with an old tire, that wasn’t very good either. With my best pellet I got 2.5″ best group at 50yards. At 35 yards killed some small old pill bottles no problem, that’s shootin within an inch so 35-40 yards is my limit for hunting off hand. If I can find a good rest to bring out I’ll be able to get some good groups at 50yds, probably about 3/4″, maybe 1/2″ with real good shootin. Just have to bring a folding table and a chair I guess.

          • And don’t think Im crazy to say the group could go from 2.5″ to a 1/2″, the prone w/ tire was the most uncomfortable thing ever, it was all gravel in my elbows, might as well of been offhand, probably would’ve been a tighter group!!

            • RDNA
              The Benjamin trail np I had in 25 cal. produced about the same results you had. And when I shoot my .25 cal. Marauder it will group half the size of what the nitro piston break barrel .25 cal. would do at the same distance. So that has to tell you something about how PCP guns are when you shoot them. Smooooooth.

  3. G’day BB

    Reminds me of the car I hotted up years ago but ran out of brakes. If you want a fast car buy a stock fast car and save a fortune.

    Cheers Bob

  4. Wow, that’s many times all the knowledge I’ve ever learned about Airsoft guns!And all in one place!
    Good job B.B.!I also really like the analogy to racing
    I rememberA guy bringing in one o’ them”Hondacars”as we referred to them at the shop, Ya know the ones with the big chrome or polished stainless $500 mufflers hangin’ out the back he’d just had a clutch installed down the road which was touted as unslippable, and was having me build a custom exhaust system from his brand new header to his also new muffler.The car was absolutely a magnificent specimen of what aftermarket engineering can do, in every way but one! When it came time to pull it on the rack.
    The front tires spun so ferociously that he couldn’t get it lined up correctly until the smoke was so thick that he could no longer see his target!

    Absolutely hilarious!!!
    or maybe even Priceless
    definitely a fun Day! 😛


  5. Not long ago, I spotted a box of Airsoft gun parts in a local thrift shop. On further inspection there were a few that were fairly intact and one which was obviously an abandoned attempt at building one from a kit,I also spotted an Estes Prospector-23 inch model rocket on the way to the counter which I grabbed and presented as a bundle deal
    Total price=$4
    Does anyone else want to launch this rocket? 🙂 I picked up a buncha motors just the other day!


      • Ain’t no way I could’ve come up with the money to buy a rocket , let alone engines for every performance back then! All my money went on bike parts,whether mine or my friends’.We all Always had at least one fully functional bicycle because I had a stack of parts about 8 feet high in my back yard and anything not found there is where almost all my lawn service money was going, except for the occasional pack of BB’s or fishing gear. There wasn’t even much for candy or sodas coming outta this fund, All business!


      • Gunfun
        Yep me too, I would buy the little single motor rockets that should use an A motor and put a C or D motor in it and watch it just about disintegrate during flight because it could not hold up to oversized motors thrust or buy the one with a payload section in the nose and catch mice or frogs to send into space. Remember I grew up In cocoa beach FL the home of Kennedy space center and NASA so we had our own launch pads and mission controls. It was great watching the Apollo and Gemini space missions go up and the Saturn 5 rockets would literally shake the ground like a earthquake and cause items to vibrate off shelves in your house when they were launched. There was to mission that went up at 2 in the morning and could be seen as far north as Virginia because there is cocoa beach it be make you think it was 2 in the afternoon it was so bright it resembled the sun when they were launched.

        • buldawg76
          I bet that was something to watch them launch those full size rockets. I would of loved to see that when I was a kid. Well even now. 🙂

        • The first rocket I ever bought was for a christmas present to my niece, it’s maiden voyage was attended bythe whole family and was the source of many exclamations which should be rated all the way from G to XXX!This was enough to inspire me to purchase a kit for my nephew’s birthday which I built myself, so not to let the cat outta the bag. Since then I’ve been hooked!I have built at least a half dozen others since,totally from scratch and anyone interested is always welcome to any launching ceremony held.
          Have you ever watched October Sky? It reminds me of what we do here on this blog!-Throwing ideas around for discussion by anyone willing to participate and such.

          • Reb I still remember my first c size rocket I shot.

            When it launched I was sitting there watching it go higher and higher and higher and I could verily see it. Then all of a sudden you could here a slight pop and see the smoke puff way up in the sky and the parachute opened. And it was a beautiful clear blue sky day. And my rocket floated away. Never did find it. But after that I cut about a one and a half inch diameter hole in the center of the parachute on the rest of my rockets I made.

            That was sure good times doing the rockets too back then.

            • GF1, thanks for the chute tip! I’ll have to try it. After losing one such rocket over the fence for Dyess AFB,and having to explain this to the security supervisor I’m no longer so interested in high altitude launches any longer and prefer rapid and intact retrieval instead. Yeah, it really happened. 😀

              ~Go big or go home~

  6. I used to run a small airsoft field here in Brazil. The only time I had one of my guns upgraded was a G36 that got its internals damaged during a skirmish. I installed a full upgrade kit with gears, pistol, guide, instead of replacing just the damaged part, but continued to use the same mainspring, because I didn’t want more velocity.
    On the other hand, the vast majority of shooters who brought their own guns for the matches had some type of up-grade on their guns, very often they would be disappointed at the numbers they would read on the chrono screen. Seems like “airsoft custom shops” in my area are promising numbers they can’t actually match. Don’t even mention accuracy…
    Another question, BB, not related to airsoft: how can I discover the ballistic coefficient of a given projectile? Is there any data source on the BC for the various bullet configurations the you know of?

        • GF1, It’s a 2 stroke nitro-methane machine gun simulator design illustration.Too bad you can’t see it! Guess you’ll have to dig it up on your own.Sorry,I tried.If you can find it, lemme know what you think .Good luck Bro!


            • Just in case it never gets brought up again. for whatever reason. It appears to basically be a spring piston powerplant with a reservoir filled with a “combustible’ liquid’ which is metered into the combustion chamber every time the piston is retracted. It would basically be a 2 stroke nitro-methane diesel engine! cocking could be performed manually or by any other means dreamed up by R&D techs.Electric motor was my 1st idea, however this would put our firearm in a category that’s uncomfortable to me(ATF would have our lunch!) experimentation with different combustible liquids in a search for the best candidate would be where I would start . and not with nitro methane.After all who wants that powerful an explosion occurring 2” from their face? This would be the main reason for my reluctance to share this design with power hungry thrill seekers such as ourselves(Approach with caution!)but I really hope you can find it because there is no way for me to come up with the 1000 words supposedly necessary to translate this picture.

              Good Luck!


    • Reb
      I checked out the nitro gun schematic you showed the link to. it would not open from the link you provided but it did when I copied and pasted in my browser. that looks cool except for the fuel part as I to an very insecure of having the time bomb element of having nitro methane that close to my face. I mean that’s a lot of energy in a close proximity to our bodies. It make Me thank about the Nissan Leaf electric car and having to do any work on it with a 480 volt electric system capable of releasing 3000+amps if you make a mistake you do not get a second chance if you screw up. I believe it would be the same with that type gun although it would be way cool to have one I just wonder what the muzzle report would be like. You may very likely be deaf after a shooting session even with ear protection

      • Bululdawg, I like your plan for the slow and steady tune on your XC60, mostly because it kinda sounds like mine. I am also currently realizing the limitations of pump guns regarding ease of charging by individuals with physical difficulties.My Red Ryder has been getting worked so hard, since I’ve gotten back, I swear it was still glowing from the friction when I went to bed last night!I really like the XC60 because it can remain such an inexpensive and reliable alternative to guns 3 or 4 times it’s price or you can invest a little education, sweat and maybe a few parts and actually compete with these more expensive guns in terms of performance.
        My end goal being the latter!
        Good Luck!


        • Reb
          Being a master mechanic by trade I always do my own work for three reasons 1. I don’t trust anyone else to do the work to my standards and perfection expectations. 2. I like the self satisfaction knowing I figures it out and did it my self. 3. I will not trust mine and my families lives to some one else that is just doing the work to make himself a living. I learned many years ago when I work for fifty percent of the labor as a mechanic at the first independent shop that if you are not willing to take the time to do the job right the first time then where are you going to find the time to do it right the second time when you are not getting paid because it is a comeback. There is a saying in the auto repair world that states “fast is slow and slow is fast” or “work slower to work faster”. There is very little in the way of electrical, mechanical or hydraulic that I cant take apart inspect and study and come up with improvements to increase the performance and durability of because to mass produce something there are always compromises that have to be made to build cost effectively. I on the other hand am not concerned as much with cost as I am with perfection and performance. I am anal when it comes to my bikes and guns( my daily drivers only get required maintenance to keep them reliable.). Us old biker have another saying and this is the cleaner version to be acceptable for this forum ” if you don’t ask to ride my bike I won’t ask to sleep with your wife” . My goal with the60C is to have a gun that is on par if not better than a disco or marauder. There is a guy on the GTA forum that is doing machine work on the 60C breach and barrel to accept a Mrod or Prod magazines to make the 60C a repeater. He quoted me a price of 110 bucks to machine my breech and barrel to accept the Prod magazines, they only hold 8 pellets versus the ten in the Mrod mags but they will allow you to shoot the longer heavier magnum and jumbo exacts in the mag. That’s why I am looking into my own mill,drill. lathe setup to be able to do my own work, back to that anal perfectionist thing again.

          • buldawg76
            I’m right with you on everything you said. I will not even let anybody change the oil in my vehicles.

            And I have been a machinist for over 30 years. So I like to make stuff. But you know what. I still don’t own a Bridgeport or a lathe. Only because of the fact that the shop I work at lets me use their equipment. And believe me I have. But it would be nice to get some equipment to call my own.

            I can just see my self going into work after I retire and asking if I can use their stuff. So maybe that’s what I should start saving my money for. I cant imagine what it would be like without access to that equipment.

            • Gunfun
              You say you can do projects of your own at work on your own time.it was the same way at Harley and I took a two year machinist class given by one of the mechanics there that was a machinist before he got the job at Harley. I learned a whole lot in that class and is why I want 3 in1 because we trained on a Smitthy granite 3 in 1 and it did very good work. We had two projects to complete to pass the class, one was a 3 by 3 inch 1/2 inch thick piece of flat steel that we had to drill like ten holes in with some threaded and some not and thread studs in the threaded holes and when done our teacher had a master jig that he would use to mate to the piece we made and if the two pieces fit together perfectly you passed that project. The second was to machine a 1.5 by 1.5 block of steel down to as close to a 1 inch square block as possible, mine is within .0005 ” of being one inch exactly. So that is not bad for a 3 in1, I have read on a lot of forums that 3 in1s are not worth the money and are junk but I know better. It also helped that the table we put that 3 in 1 on was built by our teacher from heavy steel with adjustable length legs so it could be leveled perfectly and minimize any vibrations as Our teacher/ mechanic was like me and very anal about doing the very best at anything he did.
              I have a questions for you I have drawn up a blueprint of the fill adapter I want to use on my 60C to include the installation of a gauge on the gun, would/could you possibly be willing to make the part for me as I will not be able to afford a 3 in1 in the real near future. I am willing to pay you for your time and I have a 1 inch dia by six inch long piece of 7075 aluminum for it to be made out of, if you will let me know and I can send you the metal and blueprint for what I want. If you want one of those 60C PCP guns all Mike has left in the 100 dollar guns are 177s and those don’t have a safety just like mine but you can add one from the new gen 2 guns with a small clearance made to the stock. The gen 2 guns are in stock now with safety installed but are now 165 bucks, so if you want a 22 it will cost 165 instead of 100 bucks. I got one of the last gen 1 22s he had. Let me know about the work for me
              Thanks Mike

              • buldawg76
                I missed this for some reason. And Im pretty sure I could make that valve for you. But I have to say since it is a valve for filling HPA I dont think I would like to mess with making that valve. If it messed up while you were using it. Well that would be not good. I wouldn’t want to be resposable for something like that.
                And I would be interested in one of the guns in .177 cal. so I’m going to check it out.

                • Bunfun
                  I fully understand how you feel about making a part for someone and something happens that could lead to a tragedy. I would feel the same as you if the roles were reversed, I just thought I would ask. I thank you for your honesty. I wasn’t sure what type of machines that your worked with so I thought I would ask your opinion. You definitely work with large machines because the only name I recognize is Brigdeport. If you are going to get one of the 100 buck guns you better hurry cause I don’t think he has many left.

                  • buldawg76 thanks for understanding about the machine work.

                    And I’m going to check to see if he still has one of the 100 dollar .177 cal. guns left. I need a pcp gun that will operate 2000 psi and under. That way when my little 88 cu. inch tank dont have enough air to fill my 3000psi guns I can keep shooting with lower fill preasure gun.

                    • Gunfun
                      My 22 shot very good right out of the box in the 800 t0 850 fps range with about 20 shots in the 1500 psi fill level. I think you will like the gun they are actually quite well built for the price and I believe Mike does a test fire of every gun he sell so it will have some air in it when you get it. The 177 will probably be up in the 900 fps range out of the box. let me know when you get one and what you think

              • buldawg76
                I just ordered a first design in .177 cal. Cant wait for it to get here.

                And I have to ask this. How loud is yours so far. And have you noticed a change in sound since you started tuning yours? Like getting quieter or louder. Just curious about that.

                • Gunfun
                  My 22 was pretty loud when I first shot it right out of the box and you can tell by the report when it gets on the power curve of the valve tune. Since I have modified the hammer spring tension and valve spring it is quite a bit louder especially when it comes up on the sweet spot of the tune, it is very close to being as loud as a real 22 long rifle and probably is about right between a 22 long and 22 shorts report. So it has a very sharp crack on the peak of the tune. I don’t live where it is a issue with my neighbors so I am not concerned. I can’t really say about the 177 you just bought (congrats you will not be disappointed) because I have not heard one and I own mainly 22 guns. it all depends on whether you tune it for power or for shot count but is will have a decent report. Let me know how you like it when you get a chance to shoot it.

                  • buldawg he has the 100 dollar .177 in back order. I’m supposed to get mine around the 14th of this month.

                    And I did some checking And the .177 gets a pretty good shot count at the factory setting. What I want to do is use a 10 grn. JSB pellet and slow the gun down to around 800 fps and try to get a quieter gun ( I did that with some playing around with a .177 Disco I had). So that’s what I’m looking for. And of course I would like to get it to hold close to a 1 inch group at 50 yards and under bench resting it. I mostly plink anymore and I have to take out a few pesky starlings at times. So that will be what the duties of the gun will be. All I know is it will be fun to tune. Its going to be a long wait though till the 14th that’s for sure.

                    • Gunfun
                      The waiting is like a kid at Christmas when you know what one or two of your present are but you can’t open them till that day. It will be worth the wait. While your are waiting you may want to got the Gateway To Airguns forum and sign up because they have a blog dedicated to the FD PCP gun with a lot of good tuning info and breakdown pics if you are not already a member. You can get to four of the good info post without joining from the Fling Dragon web site when you click on tech info link and then on the XC60C GTA links. It is free to join and I know that is where I have gathered most of the tuning mods that I have done and also came up with some of my own. If you are going to tune for power and want to fill above the 1500 psi that is recommended the first thing I suggest you change it the two screw that support the hammer block and valve in the tube as they are of unknown grade of screw and should be replaced with some grade 8.8 metric 5mm X 0.7 pitch allen head screws. I spoke to Mike at FDAR and he has tested the tube to 4000 psi with out issue so I am comfortable going to 2000 psi with replacement of those two screws and you can get them at most any hardware store. Any way I know you will be happy with it and if you need any tuning info or disassembly help shoot me a message,

                  • buldawg76 it was getting thin on or replies so I moved up here I hope.

                    I have already been checking out the gateway forum. And I’m actually going to slow mine down when I get it. Less power. My main concern is accuracy and then have it produce a fair amount of energy. I’m thinking somewhere of about 15 to 18 fpe with the 10 grn pellets is what I’m going to shoot for. And hopefully that will help reduce the sound of the gun also. Will see. But I will definitely holler at you when I get it. And I’m sure I will have some questions. See ya around.

  7. I wonder if this type of system could be used to power a pellet rifle? Everything would have to be stronger of course due to the power. Perhaps it has been tried?


    • Maybe it’s time to find a patent lawyer and approach whoever came up with the original concept and design?
      Should be plenty of $ to go around.
      (Just couldn’t stop thinking about it .)


      • Mike, engineering was pretty much as abstract a thing as I could imagine also, until the drafting class I opted for during my senior year of high school.However, Once the parameters are set it now appears to me, nothing more than an idea,initially transferred to paper as a design, which creates the questions to be addressed for further development of the design, leading to ultimate success.
        I hope that’s clear enough t get you past the stigma, I tried to leave out as much gobbleDguck as possible.
        If seeing the design compels you to ask a question like the one you have just asked,you have ‘The Right Stuff!’Jump in and “Git Sum!”

        Good Luck!


  8. Oh man, Reb, I can see you doing the peepee dance! It must be all the coffee… take two and speak to the doctor in the morning, lol. But if you do use all that energy to build a full -o-matic pellet gun, let Mr. Holdover run it through some cans and pigeons, that’ll get you going quick. Im going FX on his and gunfuns recommendation. He shows a full awe toe pellet gun on one of his videos, but I forgot what it was, but it ran very well. Always need a model to create something, even if its just a mental image. See how the fullys that are out run and it might be something easy to add to an existing gun of yours your willing to risk……

    • RDNA, I love Ted’s videos! As a matter of fact, that’s where I got the inspiration to turn my 760 into a poor man’s Verminator!

      Thank You Ted! Wherever you are.

      Richard Ribble,
      AKA, Reb

    • I still have that Tippman 98 lying around, I just wish I had access to the information on how Air Ordinance turned it into the SMG.22 so I’d have an idea of where to get started, or a drop in kit, so I didn’t have to build it from the ground up

      • It sounds like an airsoft drop feed system could be fitted in somehow, and 6 mm is close enough to 5.5 they should feed fine, then a barrel fitted right in to the existing barrel and mate them together like a drop feed would go with an airsoft barrel. Might not have to change much but square out the existing paintball feed port(breech). The only real problem I can picture is getting the air to hit where you want., maybe a tube that sits where the paintball sits when fired, ported for the feed, sealed to barrel. How to get em to feed one at a time will take some work but that’s where an existing gravity feed mechanism from an airsoft might be best.

    • RDNA
      Are you talking full auto FX guns?

      I watched some video’s of FX guns that they say they changed over to full auto and nobody shows the bolt cycling. They just show the gun kicking a bit in a medium fast fire. I could pull the trigger faster on my Monsoon then what the video showed. And to me I think they are bump firing the guns that I seen in the videos. But they never show a view of their trigger finger either.

      You know if a gun is a true semi-automatic and not a repeater that its pretty easy to convert one to full auto. But you better be ready to pay if the big guys find out and you ain’t got a licence. I wonder if the same applys for pellet guns?

      But here is a neat bb gun that people mod the heck out of. Check it out. The video is only about 5 min. long I think.

      • Also I forgot Teds holdover has some good videos. I will see if I can find that video your talking about with the full auto FX guns.

        And when the Evonix guns came out they offered them in a full auto version then all of a sudden you couldn’t get the full auto version anymore. Just semi-auto. Well if I’m remembering right it was the Evonix brand.

      • Gunfun
        Can I please can I can I can I please please please can I have one. That is the BOMB . Man I got to check it out and see what it costs . I just bought a 47ci bottle and regulator off ebay to use the reg on my fill station for my XC60, but now I think I will keep the bottle and buy another reg and get one of those , man that is the best thing since sliced bread. just think what a criminal would do if he broke in your house in the night and you peppered him with 1000 bbs at the 1200 fps setting for like ten minutes. WAY COOL

      • Gunfun
        I just checked out the video of the Drozd blackbird and priced them on the site 299.00 is not that bad for one. they say to get the most out of it you need to use 15 volts and a 3000psi source. There is a good place to use Lipos for battery power and attach a paint ball bottle tether tone and you can get 1600 fps and about 20,000 round shooting between fill in bottle and battery pack charges. I got to get one but I just bought a 1122 ruger camo from targetsportsusa.com for 180.00 with free shipping so the blackbird will have to wait till I get some gun side work done to pay for it.

        • buldawg76
          I have many,many times almost got one but haven’t yet. I don’t know why.

          I do have one of these and it is very fun little plinker. But not as thrilling as a hopped up Blackbird.

      • Wow, that thing looks like a blast! And anybody that thinks you couldn’t defend your home with an airgun should see things like this, that would certainly send an intruder heading for the hills! Plus you wouldn’t end up in court defending yourself for a self defence trigger pulling… there was a guy in a store the other day looking at co2 pistols for his elderly mother to have while he was traveling for work, said she wanted something but didn’t feel comfortable with a firearm, lot of break ins in their area. Not the best idea but I guess if they feel better with one, that’s what counts. Something like that would actually be effective though, 1200 rpm and 900fps? Yeah, that’d work if a firearm wasn’t an option.

        • RDNA
          And now days it seems anything fun ain’t cheap. But the Blackbird and a few extra bucks and you got a fun gun you know. I really need to add one to my collection. Maybe that will be The second bb gun I own.

          Couldn’t you imagine having one of your buddy’s that shoot firearms come over and give one a try. I don’t see how they could not be impressed with one after they shot it.

  9. Do the pyramyd deals emails go the same to everybody or are they customer specific? Because the Evanix max-ml bullpup ad I just got is too perfect, that thing looks sweet! Might have to get that and a FX bobcat and compare them… In tossed between wanting to buy from pyramyd and wanting to support the motherland… solution? Buy both! Then when its time to pass one down to the grandsons I want be without, that’s a ways away but my daughter will be shootin within the decade, what’s a good age to pass on a thousand dollar airgun? When In dead sounds good! Lol

        • I havent seen a automatic version offered anywhere. Im thinking the gun is modded. Somthing about adding a spring to the safety lever on the left side of the gun. Thats what you see the person in the video moving.

          • Is your monsoon as quiet as that? It looks like it sends a tight group, I was going to say, getting shot to shot consistency is probably the most important converting to full. How bout the guys fancy target box? Nifty little storage area and all, now that’s serious multitasking from a trap… Puts my duct seal box and messy drawer full of used target’s and index cards to shame. I quit buying real targets at 5-10$ for just a few when I can get a few HUNDRED index cards and draw whatever kind of target I feel like. I bought two packs like 3 months ago and ain’t running out any time soon. 1.60$ for like 500. Its cool too when you want to do a certain thing and can draw your target to work for that. Like comparing two pellets? Draw two bulls, sighting in close? Draw a stacked crosshair bull combo deal. Draw a squirrel with distance relative killzones, stuff like that.

            • RDNA
              My Monsoon is quiet. They have a shrouded barrel that encloses part of the mechanism to cycle the semi-automatic action. But my Marauder rifles are quieter.

              And that is a nice little pellet trap they got. I would like to have one just because of how cool it works.

              And you talk about grouping when firing automatic. Well you know the old saying if I’m saying it right. Spray and pray. I don’t think anybody trys for groups when they fire automatic. That’s why most automatics have a selector to change to semi-auto mode. Automatic with a air gun would probably be for some exciting plinking I would think. Then you would put the selector on semi-auto for your hunting or target practicing. That’s my opinion anyway.

      • Super Sweet, but as Dave mentioned above I ain’t got no $5000 to be blowin’ on a machine gun and am focused on building more patience,so I’m much more willing to build my own with the money instead.
        But wouldn’t that be Awesome?!!


  10. I may just have to put the Marksman.0035 on the back burner for a while. When I went to check it out earlier today there was a newbie that had been added to their collection as I handled the gun I felt quality,however the only marking on the gun read Stealth. I inquired as to the manufacturers identity only to find out that it is another modified Tippman(like the SMG.22)!
    $60 cash or $11 layaway!

    Things are looking really good for me right now,&I consider myself to be very fortunate for what I’m considering to be a second or maybe even third chance at a whole new and improved life!:)


  11. I’m discovering the curse and blessing of a chrony today. I just got a Hatsan 135. Advertised as .25 cal 750 fps. Best I could get is 715.2 fps. So I’m feeling a bit lied to today. I really wish that the airgun companies would advertise what the gun can do based on actual results than publish what their advertising people that likely have not even seen the gun say it will do by artificially inflating the claims. It would help out air gunners quite a bit to have actual results so they know what the gun can actually do. Granted the lie sounds better than reality and is good for sales but if I believe the lie I might expect the gun to do what it really cannot do.

    • John,

      Hatsan is one of the few companies that advertises velocities using real lead pellets — not alloys. To be honest with you, 715.2 fps isn’t that far off from 750, and I would expect that you will get some shots that reach 750 fps. Remember, these are max velocities. Guns vary one from the other. No two guns will have exactly the same velocities. Also, the lighting conditions during chronographing will impact the readings. Lots of variables. Lastly, you said you just got your Hatsan 135. I’ve read more than one review from owners of springers who bemoaned lower-than-advertised velocities, and then had to recant their reports because velocities started to increase as the gun was broken in.


      • I’ll keep that in mind and see what happens after I throw some shots through this gun. But it is a very fine looking fun. In fact one of the finest looking guns I ever put eyes on.

      • I don’t recall what they used but I bet it was a light one. I’m using what ever I had on hand which was JSB exact kings. What really got me was my custom disco in .22 generates much more energy than the 135 in .25. I guess a hand built gun is better vs. a factory made one when looking at down range hunting results.

        • John
          So you did finally get a chrony. I have been waiting a long time for this moment. What did your Disco that you modded chrony at. And what pellet and what weight was that pellet?

          • I finally did get one. Using 19.09 grain Baracuda hunter extremes I’m clocking an average 861.78 and a respectable 31.49 fpe 0r 42.69 joules. With 17 grain Metalmags the numbers clock an average 858.7 fps with 27.84 fpe or 37.56 joules. That is giving me enough power to chew through a 2 inch phone book and impact a cast iron pan on the other side hard enough to flatten the pellet. The disco is really not a disco any more. It now has a laser, bipod, thumbhole stock and all the fun bells and whistles. Very nice looking gun. Accuracy is very good too. This gun will stack pellets.

            • John
              I cant remember who posted the other day a big cal. conversion for the Disco’s. But if you got the fpe with a .22 cal. at 30fpe and you can stack the pellets it sounds like you got a nice gun.

              But what distance are you doing your testing at?

              • On the chrony tests I’m working inside the chrony is about 5 feet from the muzzle and I’m firing into a phone book to catch the lead. So nothing worth talking about there. But for accuracy I’m taking it out to around 25 yards on a calm day outside. My accuracy is fairly good keeping it all well within an inch or less depending if I can see straight that day.

  12. There was something I thought about after a few days went by on the $100 PCP and I left a comment there towards the beginning of that blog.

    But somebody wrote about all the equipment and things that were needed for PCP guns. And here is what popped into my mind and I did write it down on that blog.

    What I would like to see is the big name airgun makers come up with a program like what is available with propane tanks for BBQ grills and such. Or somebody come up with a program.

    I think they need to come up with a exchange program where you can just go to a department store or gas station and exchange a bottle of compressed air (small or big bottle) with a standard Foster female quick disconnect fitting. That would solve the problem with getting our PCP bottles filled.

    And I would bet there has to be some kind of issues with doing that or there would already be something in place. Maybe because of the danger of the valve on top of the tank getting knocked off. I just threw that out there for a example. But I would like to see a program happen. I would still use my ShoeBox and my hand pump to fill. But it would be nice to know you could run right down to the corner and get another bottle And get back to shooting.

    • GF1,

      Propane grills are ubiquitous, but PCPs are not. In fact, airguns aren’t even ubiquitous.

      The type of network you’re talking about would require a tremendous investment of time and logistical planning. But, most of all, it would require a serious monetary investment.

      I don’t believe the resources required for such a set up match up with the extremely limited use of PCPs.

      Plus, you have no idea how people could modify or damage tanks.

      PCPs already come with a certain risk other powerplants don’t have. I don’t think I’d want to increase my risks by bringing in tanks that have gone through countless hands and possibly people who experimented because they’re not keeping the tank and therefore have little interest in the possible dangers since they’re not going to be present when things go wrong.


      • Edith
        Good points you braught up and I hope somebody didnt mess with that propane tank Im BBQing with right now.

        And I do agree with you on how people would handle the tanks now that you said that. Im pretty picky about how I take care of my stuff. So maybe not a good idea then.

        But I sure wish there was a way to get HPA easier thats for sure without having to spend a fortune.

        • If you can use a hand pump to fill an airtank, couldn’t you have an adapter so you can fill at any gas station air station for car tires? That’s available anywhere and you would just need the adapter… ??

          • RDNA
            The hand pumps and compressors like the ShoeBox are 3 stage pumps. The first stage is air like you would get from a shop compressor or yes the air from the gas station pumps.

            But then you have to a another pump like the ShoeBox to achieve the high pressure air. That pump takes the incoming air from a shop compressor and then goes through another stage which is stage 2 and I think that stage makes about 2000 psi. Then that air is routed to the 3rd stage which I believe will go to 5000 psi.

            The pumps like the Benjamin hand pump is a 3 stage pump. It has the incoming air plus the other 2 stages to achieve the high pressure.

            The problem with filling something with high pressure is that it takes a bit of time for the pump to fill a bottle. But it only takes a matter of seconds to transfer HPA from a bottle to the gun. Which is something you don’t want to do because that creates heat and I would guess that it stresses the components in the gun also. So its very important to transfer fill slowly.

            So that’s why I was wondering about the exchange system. Or kind of like you said if there was a place were a individual could go to and fill there bottle. But the only problem is that it takes a long time to fill a big bottle. The smaller 90 cubic inch and smaller tanks are a bit under an hour to fill. And the big 80 cubic feet tank takes hours to fill from a 3 stage compressor.

            If you look at the different things available the hand pumps like the Benjamin pump are actually pretty efficient. They will fill a gun in under 10 minutes if you put it to it.

            Anyway HPA is not something that can be done with normal devices.

            • We had a diver training school here in town until it closed last season,they seem to be doing this on a regular basis so I’m ho too concerned about it. Sure hope they reopen soon!

    • Gunfun
      You can go to your local welding gas company and rent a 120 cubic foot tank with nitrogen or just compressed air for around a 100bucks a year. The local place here in AL charges 100 bucks a year and refills are fifty bucks. I did the calculation on the Airhog website and that 120 cubic foot tank will fill my XC60C reservoir 577 times using 4500 psi of compressed air in the tank and filling the gun to 1500 and refilling gun at 1000 psi. That’s not to bad of a deal, it works out to 55 cents a day to rent the tank and unless you shoot four or five fills a day it will last the best part of a year. Then all you need is the adapter to go from tank to gun.
      Yea I watched the movie October sky and it reminded me of my fun with Estes rockets.

      • buldawg
        Now that you said that I use to do that with my oxygen and acetylene tanks through the local welding supply store.

        So if I used nitrogen one of them 120 cubic feet tanks would probably do me a bit over a half a year then. So thats not to bad of a deal then.

        That was one of the things me and my brother talked about when we started using nitrous on our cars. We almost got us one of those fill stations with the big bottles. I started messing with those little 172 cubic inch positive boost under the hood blowers and turbos also. We added up the cost between how much the blower cost and how much the nitrous equipment would cost and we decided to start doing the blowers. And the blower was always there and ready to go. Where as the nitrous you had to carry another bottle so you wouldn’t run out.

        I got a ShoeBox but I think the Nitrogen would be a good alternative. I wonder if you get the same shot count when you use Nitrogen verses HPA.

        • Gunfun
          Check with your local Airgas supplier or any other large brand name welding supply shop in your area.
          Nitrogen is the best to use because it is void of any moisture and other corrosive chemicals although it may be 10 or 20 dollars more for a rental tank and it will cost a little more to have the tank refilled than plain compressed air . So you just have to weigh the differences, myself I use compressed air because its the cheapest and I have a friend that is in the fire extinguisher business and he had a firemans SCBA 45 cubic foot tank that he sold me for 50 bucks and will refill for ten bucks to 2500 psi and that give me 127 fills on my XC60c from starting at 1500 and refilling at 1000 psi. I also am regularly tearing it down and doing tuning to get better power and shoot strings from it so it gets cleaned and lubed with silicone frequently so I don’t worry about a little moisture in the air. I have only had my XC60 about o month and have not found the happy spot on the tune to give me at least 10 shots above 900 fps and at least 5 at 950 fps but I am close, I am getting 6 to 8 eight above 900 fps so I am at the fine tuning stages and just think I have to play with the valve spring tension to get what I want. I was going to rent a tank of compressed air, but ran into my extinguisher buddy and he turned me on to the SCBA tank and he has another one he is going to save for me to buy down the road. The setup he sold me was a complete system with backboard, breathing mask, hoses and regulator and I sold the mask and hose and reg on ebay for 140 bucks. Another thing to consider about a 120 cuft tank is it is 5 foot tall and heavy so it would most likely be in a stationary location, where the 45 cuft tank I got I made a homemade cart with wheels to move it to where I am shooting and it was a old Oxygen tank dolly that you see old people pulling along with them that belonged to another friends dad that passed away. I think you probably can get 60 or maybe even a45 cuft tank from the welding supply that would be cheaper but just would not last as long. Or check your local fire houses and extinguisher shops because they may have a deal like I got for cheap and all fire houses have the capability to fill a tank because they need to fill there own SCBA tanks so with a box of donuts and a little conversation you may be able to get a tank and cheap fills if you let them show you around the station and give them a small donation especially if it is a volunteer station. You don’t know til you check em out and kill em with kindness. Just some food for thought on the easiest ways to come to the dark side of air gunning, I made the switch cause it is harder and harder to be able to pump up my old crosmans with my arthritis and I aint goin stop shooting.

          • Buldawg76
            One of the places we use to get our nitrous refilled at did fire extinguishers. And 2 of the places that I had my oxy acetylene tanks filled went out of business. The local Rural King now fills oxy acetylene tanks but I don’t know if they do Nitrogen or HPA.

            But we do use Nitrogen at work to fill the accumulators on the machines that use hydraulics. I could probably work something out with that supplier if I wanted to I guess.

            I wonder if that would of been more cost effective to rent a Nitrogen or HPA tank and get it refilled. Or if the ShoeBox I have would pay for itself in the long run.

            But if I was just getting started in PCP’s again the tank rental would definitely be another resource for filling the PCP guns.

        • Gunfun
          I did not realize you had a compressor.( shoebox) I had a brain fart I guess because the term Shoebox did not register at first as I am still new to PCPs and still learning the slang. I don’t know what size tank you fill with it or how long it takes I have been filling my 60C with the pump I got with it and it takes 40 to 45 pumps to get to 1500 psi and about 60 to get to 2000 psi which I have tried the last three times to see if it would give me more shots at 900 + fps. I am still waiting for the reducer to go from the CGA347 valve fill nipple I have that has 1/4 npt and I am reducing to 1/8npt, it will be here tomorrow from Fastenal for $2.14 and I know to go slow filling the gun the 347 valve allows for a slow fill rate. I looked into all my options for filling the gun and just lucked into the firemans tank and being able to make my money back by selling the mask and reg assy. You may get a good deal with the company that fill your accumulators it would definitely be worth looking into. My extinguisher buddy said he could also fill my tank with CO2 also but I know it is more temp sensitive and I don’t want to have to worry about the pressure getting to high due to the summer temps here in AL getting into the high 90s to low 100s on some summer days and I due most of my shooting from the back porch. I did not think to ask about filling my tank with nitrogen but I will when I go to get it refilled. I just got a ninja paint ball regulator that I modified to regulate the pressure of 2500 in my tank down to either 1500 or 2000 psi when filling the gun because it doesn’t have a gauge on the gun. I found the info on the GTA forum and drilled and tapped the end that screws into the paintball tank to thread on to the adapter for my CGA347 valve nipple and can change Bellville washers in it to adjust the pressure for the gun and can get the Bellville washer for 8 bucks from Mcmaster Carr. Then I just got a valve and tether line that paint ballers use to have a bottle on their gun. I got a 47ci bottle and the valve from ebay for 27 bucks shipping included. so I have less than 100 bucks in getting a bottle set up to fill my gun with. if I were you I would use my shoebox or check out your nitrogen supplier.

          • bulldawg76
            We get the big tanks at work. They stand about shoulder high. We replace the bladders and fill them with nitrogen ourselves at work.

            And the Nitrogen and HPA from a welding shop would be the exchange program I’m talking about. Why didn’t I look into that before?

            And you talk about tuning your gun. You have to put washers or shims in with the spring to get the striker or hammer if you will to hit harder. Is that what your doing?

            • Gunfun
              I have the hammer spring adjustment where the screw adjuster is flush with the nut face with the washer removed and then put lighter spring in the valve with a homemade guide for the front end of the spring on the inside of the valve body where it just sits against the front end of body and spring did not seem to stay centered in the front of the valve because there is no seat or guide to keep spring it centers when working the valve stem by hand. The hole in the back of the valve body for the stem to come thru is not a tight fit on the stem and the valve tends to cock a little angled when you work it by hand so putting a short guide at the front for the spring seemed to help it stay more centered. I think the hammer spring is set strong enough because with no air in gun you have to cock the bolt to fill the gun because the valve is being held open by the striker. I am just fine tuning the valve spring to get a longer shot string because right now it is a bit of an air hog and not real efficient. I am getting 15 shoots between 850 to 950 fps with about 5 at 900+, I would like to get ten at 900+ with hopefully 5 at close to 950 and 15 or so from 800 to 950. I am just waiting till tomorrow when I get the final fitting to be able to use my SCBA bottle to fill with cause it is still a work out to use the hand pump to fill with. The tuning is part of the fun.
              I am looking at getting a mill/drill/lathe setup where I can make a fill adapter for the front of the tube that will have a pressure gauge as part of the adapter and make a new rear half of the valve body that is a tighter fit to the valve stem and does not allow it to cock sideways as much as it does now and will let less air escape around it, I may even put a o-ring inside the valve body to seal the stem completely. Never satisfied with something I always have to find that last little bit which I know you understand being involved with drag racing and hot rods.

          • buldawg76
            This might posting the wrong spot.

            But how is the air transferred from the valve to the barrel? Do they use a sleeve or bushing with a hole threw it. If you can make that hole smaller that transfers the air to the barrel it will increase your shot count. It will also lower the velocity but if you can hit the valve with a longer stroke or more spring pressure from the striker it will get the velocity back up.

            • Gunfun
              The barrel has two O-rings on it that seal the port of the barrel to the receiver and the valve body has two o-rings that seal the valve body port area to the receiver also. No transfer port seal like crosman and benji. I machined .050″ off the striker block that sit between the striker and the valve and helps provide some added support for the valve assy from being pushed out the back of the tube, replaced the unknown grade of valve and striker block screws with grade eight screws so I could go to 2000psi with a little more margin of safety. Yea there is some info on the GTA about decreasing port size but I would rather play with the valve spring as I don’t see a real practical way to decrease port size that would be easy and dependable, I may play with that when I make a new rear half of the valve body with tighter stem fit.

              • buldawg
                Now I want to get one of them guns to see what their made of.

                But taking some off of the striker was a good idea. Could a heavier striker be made easy? Like one out of brass. Well I guess I shouldn’t say easier. I’m a machinist and I have access to the equipment. But I know that helps so you don’t have to run a heavier spring.

                And I guess if you cant do anything with the transfer port size then playing with the spring pressure in the valve is the only other way. Well and fill pressure.

                And like I should get me one of these guns to play with. Sounds like it could be a fun little gun to mess with.

                • Gunfun
                  I guess my description was a little confusing. There is a block that sits between the hammer (striker) and the stem on the valve that help provide some needed support for keeping the valve assy in place in the tube because the valve has only one screw holding it in the tube so there is a block that butts up against the back of the valve assy with another screw to hold the block in place and therefore help keep the valve assy from being moved in the tube by the HPA. I was calling that block the striker block ( hammer block) because that is what the hammer hits when the trigger is pulled. there is only .050″ lift on the valve with the hammer block in the original thickness so I machined .050″ off of the hammer block to provide .100″ lift on the valve to increase amount of time and volume of air allowed past valve before air pressure closes it. I have the hammer spring set so it holds the valve open form spring pressure with no air in the gun as in a pumper set up to full dump when fired. So I am going to just adjust valve spring tension to give me the highest fps and fpe with the least amount of air possible to get the best efficiency and power from it. I hope that explains it a little better.

                  • buldawg76
                    Yep thats was what I thought you meant about the valve and striker. But sometimes it helps to put a heavier striker/hammer in place. And then you dont have to run as much spring preasure. It will help give a pcp or pump or C02 gun a smoother action sometimes also when you fire the gun.

                • Gunfun
                  Since your a machinist can you give me your input on which 3 in1 would be the best in the 2000 grand and under range, I have looked at the Smithy Midas LTD and the Bolton AT 750 and Bolton AT520, are there any others you can recommend. I know the Smitthy granite we ad at Harley was a good one but they are more than I want to spend or do you think going with a lathe and separate mill would be better. The machining on the hammer block I did on my 10″ craftsman bench top drill press and the 1/2 inch mill got hung during milling because the hammer block is a hardened piece of steel and it bent the spindle . I know a drill press is not designed to be use as a mill, but it has worked well on the pieces of brass and aluminum I have done. I know not to use it on steel anymore. Luckily its a craftsman and a new spindle was only 35 bucks, it also bent the 1/2 end mill. live and learn. give me your thoughts

                  • buldawg76
                    We dont have any of those. The manual machines we have are Bridgeports, Alliant, Harding and LeBlond.

                    All the production machines are vertical and horizontal cnc’s and Hydromats.

                    I havn’t used one of the machines your talking about so I can’t give you a answer about them. But the machines that we have can do some heavy stuff. And we use mostly carbide drills and carbide insert and holders instead of knee tools and such. We stopped using high speed tool steel along time ago also.

    • GF1,

      The exchange program was tried twice in the past. In both instances it failed and caused the companies to go out of business.

      First was thew Giffard CO2 guns in the 1870s and the second was the Wentzel air pistol of 1950. Nobody wants to return tanks. They either want to fill them themselves or they don’t want them at all.


  13. I thought everyone should experience a machine gun so I bought a full auto M4 airsoft gun. It was kind of disappointing. As a cheapo, the red dot sight could not be adjusted to point of aim. But the main problem was that the gun sounded like a typewriter. I just didn’t get anything out of it. I pressed the trigger. The gun hammered. And I saw all my money go spraying out in the form of tiny plastic balls.

    Main springs for pellet guns are something to behold. The spring for my IZH 61 which is one of the lowest powered springers is so stiff that I cannot bend it at all with bare hands. I can’t imagine the spring for my B30 which probably looks like it was carved from solid metal.


  14. rifled dna, several decades ago, the American Rifleman ran a story about a burgler who was confronted by the homeowner. He had a .25 acp pistol, and he hit the burgler with every shot in the magazine. The burgler picket up a fireplace tool and killed the homeowner. When the case came to trial, the crook was able to prove self defense (he had the bullets and the doctor who removed them as evidence.) If you are going to protect yourself, you better have a weapon that can stop a bad guy (or kill him). Otherwise you are just giving him an excuse to kill you, and walk out of court a free man. Of course, the sight of a gun (bb or real) might be enough to scare a burgler, OR NOT, and you could end up dead. I welcome other bloggers opinions re self defense with non lethal “weapons”. What would you do if your soft air (or BB) gun hit him in the eyes? He would sue you for everything that you have. Ed

    • I absolutely agree that nonlethal is risky, its not your best bet, but firearms aren’t always a legal option. Plus killing a burglar will have you on the edge in court regardless. About whether I hit em in the eyes? I would hope so, cause that’d be just where Im aiming. That’s if I was (very unlikely) using an airgun. I doubt I would be reaching for a bb gun if my window got smashed and someone was climbing through it, the machete is faster. I don’t have firearms so if they do Im in trouble anyway, but you’d have to actually make it through my window first, and honestly I don’t think they’d make it in one piece. My wife and kids will be protected, no matter how vulgar a display of power. I live in a pretty crappy area and actually have to think about these things.

  15. zimbabwae ed
    When I worked for Harley at a test facility our riding gear supply person was a retired police officer and this was before bullet proof vest were readily available to police depts. He wore a heavy Harley leather jacket that was made of 1/4 to 3/8 thick leather that weighed about 35 to 40 pounds, it was a top of line leather motorcycle jacket designed to prevent the rider from getting road rash in a accident. He wore this jacket while he was on duty and told me about the four time he was shot at by a criminal and were using small caliber pistols like the 25 acp and a 32 special caliber and also a 380 cal while wearing that jacket and the bullets bounced off the jacket. So if you are going to use a pistol for home protection I strongly suggest that it be nothing smaller than a 9mm and preferably a 38 as these have enough power to penetrate even the thickest of leather jacket. I also own a Harley jacket that is 1/4 to 3/8 inches thick in the back and chest area. I was raise by my father that in a home invasion situation to shot first and ask questions later, I personally have a 12 ga shotgun with 8 rounds of 00 buck in it next to my bed with a flashlight and green dot laser mounted on it with pressure switches to activate the light and laser in an instance and who ever breaks in my house at night will be met with a blinding light in their face with several rounds of 00 back right behind the light coming on and I shot to kill not wound. I also have a 38 revolver and 22 magnum loaded in the drawer of the night stand. here in Alabama we have a stand your ground law that give is the right to defend our property with deadly force if we feel are life is in danger and it includes your whole property not just inside your house. So I pity the idiot that breaks into my with me home because he will not leave my under his own power it will be on a stretcher to the morgue. Dead men don’t sue.
    That’s just my stance and opinion if you are going to break into my house you just put your life in my hands and I will not hesitate for a split second to pull the trigger you can take that to the bank.

    • You may have said it better than I, yes I do believe. Killing a burglar is self defence of your life from the first second, any court case that lets a wounded robber off on top is a failure of our justice system, and while the bible says follow the law, it also says don’t suffer fools. I want be thinking about what some judge has to say later when my family’s lives are at stake now.

  16. Hi,

    I have seen a great deal of info about the pellet speed, FPS, but have never seen a ratio of that to the mainspring of any type of airgun FPS to the pellet. Does anyone know? For a project I need to know how fast (max achieved) a mainspring in a std air gun unfurls. If there was no piston can a spring go 150 FPS? 200FPS. Does anyone know?


    • Darp,

      Welcome to the blog.

      The answer to your question is not straightforward. Pellet velocity does not always increase as spring strength increases. In fact, I can show where it decreases.

      Mainspring strength is one component of an entire package that includes piston stroke length, transfer port diameter and location, piston weight and other things.


  17. Thanks BB for reply! I have been somewhat mystified at finding a reference to spring speed. Have searched for hours and never found a speed attributed to the spring. The ratio of the bore of eh piston to the pellet should give rough estimate. Am guessing maybe 20 to 1, so maybe eh spring goes 50 FPS? But there is drag and compression of air issues.

    Have even contacted the Spring Institute. They gave me a formula, but do not know enough to use eh formula. It is below. If you have ever heard any figure for spring speed I am most interested.


    This as with most spring questions is best answered by your spring manufacturer who has the industry knowledge as well as experience in the unique action of springs and specific materials to clearly answer your questions. The basic information presented is available in the literature about dynamic actions of springs with regard in acceleration.

    Basic Velocity Calculations

    v velocity

    vm ultimate attainable velocity

    k rate of spring

    g acceleration due to gravity (32.2 ft./sec.2

    P force in lbs.

    Ws spring weight

    G shear modulus

    p density

    S stress

    F deflection

    √ squar root of

    For springs with a mass ratio (P/Ws) >4

    v= F √ ( kg/P+1/3Ws)

    For springs with a mass ratio (P/Ws) between 1 & 4

    v= F √ ( kg/P)

    Lynne Carr

    Executive Director

    Spring Manufacturers Institute

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