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Resizing a mainspring

by B.B. Pelletier

I recently started writing more reports about the fundamental things that many airgunners would like to know. These are things you don’t have to know to shoot an air gun; but if you do know them, they can often help you recognize why your gun does what it does. You also don’t have to know what makes an automobile work; but when it stops working, sometimes knowing how it’s supposed to work can help you find the problem and fix it.

Today, I’m going to show you how a brand new mainspring is set to its operational length before installing it into a spring-piston airgun. It’s not necessary to do this; because, over time, the mainspring will automatically reduce in length after being in the spring gun under some tension and being compressed many times. If you do this first, it makes the job of spring installation easier in some cases.

When a coiled steel spring is wound, it ends up being longer than it will after some use. Robert Beeman wrote that the surface of the wire in the spring is oriented like strands that run along the axis of the spring wire and twisting the wire into a coil twists those strands unevenly.

As the spring is used (compressed and released), it shortens (the coils get closer together); but until they do, the spring coils will be separated a little farther than they should be. If the spring has many coils and each is separated a little more than it should be, the overall length of the spring can be up to several inches longer than it should be. Once it assumes its final length, it will still have the same strength as when it was longer. It will just be easier to work with.

Not all scragging is done as I’m describing it, so please focus on what I’m presenting here because it applies to spring-piston mainsprings. Scragging is the English term for what many spring makers call “set removal.” Set removal, or scragging, means compressing the spring to its solid length (i.e., all coils are touching, and the spring cannot be further compressed). Once it’s done, it allows the spring to operate at a higher load capacity without overstressing.

Spring-piston mainsprings are almost coil-bound (fully compressed) every time the gun is cocked. In fact, measuring the potential overall length of the compressed spring and determining whether it can be further compressed is an aspect of spring-gun tuning. Tuners often install washers that decrease the length that a mainspring has to compress, just to get the spring closer to its coil-bound state when the gun is cocked. They’re trying to wring out all the power the spring has to give when they do this.

This practice will put the operational length of the spring very close to the stress limit of the spring. If the spring is scragged, the stress limit is set at the spring’s fully compressed length; so if the spring never gets compressed quite that far during operation, it stays within the bounds for which it was made. It will, therefore, last a long time. While it’s impossible to compress a spring that has been scragged past its operational limit, you can compress it right up to the limit. I personally like staying on the safe side of that limit.

We learned how to measure the length of a compressed mainspring in the recent report titled The spring-piston power plant. You learned a technique that tuners use to determine the compressed length of the spring by measuring the wire diameter and counting the number of coils. The method I showed is not absolutely precise, but it will get you within a few hundredths of an inch, which is usually close enough. However, if you want to go all the way to coil-bound, you may have to adjust the length of the spring by adding washers to take up some of the space in which the spring exists. You can then fine-tune this length by removing some washers or even by thinning one of them, if you choose to go all the way to the coil-bound limit. If you stop just shy of that limit, your mainsprings will always fit inside your gun.

A scragging tool
In industry, scragging is usually done with a hydraulic press, but there’s an inexpensive way to do it. Just use a long piece of threaded rod with two washers and two nuts, and tighten the spring between the two washers. I showed that tool in the blog last week.

A simple tool for scragging coiled steel mainsprings.

When you tighten the nuts, you’ll notice that the spring really wants to twist. You have to hold both nuts with wrenches, and they will try to get away from you as you try to tighten them. This is spring torque, and sometimes it can be felt when certain spring-piston guns fire.

This is important!
Look at the photo below of the spring-piston powerplant. The compressed mainspring has to fit inside the piston and between the end of the piston and the base of the spring guide. That is the entire length in which the compressed mainspring must fit.

The mainspring fits inside the piston and goes back to where the trigger begins — minus the base thickness of the spring guide that isn’t visible in this picture.

What you cannot appreciate from the picture above is what the mainspring looks like when it’s compressed. But when you scrag the spring, the shape jumps out at you. The spring tries to squirm away from the force that compresses it.

Here is the mainspring before it’s in the scragging tool.

The spring has been installed.

The spring is compressed almost as far as it’ll go. Notice how it wants to curve away from the in-line force that compresses it? That is what happens inside your spring-piston airgun. Only the piston and spring guide prevent the spring from looking like this.

The mainspring is completely compressed. There’s still a slight curve to the spring, which the inside of the piston and the outside of the spring guide will remove. Leave the spring in this tool fully compressed for four hours and it will be scragged.

What’s happening inside your spring-piston gun is that the mainspring is being held compressed between the piston and the spring guide. The more room there is, the kinkier the spring will be when compressed, and the more room it will have to shudder and shake when it expands. You will feel that as vibration. Remove the extra room, and you remove the vibration.

A word on springs
There have been comments on this blog in the past about stretching springs to increase their power, and I want to address that now. You can’t stretch a spring and increase its power for more than a couple of uses. What will happen if you try is that you’ll cause the premature failure of the spring. One or more of the coils will collapse, resulting in a canted spring. The results will be greater vibration and less power.

The metallurgy of a coiled spring is very precise and has not been covered in this report. There are things like forming techniques, heat-treatments and stress relief that are part of what make a spring capable of doing what it does; and while it’s possible to change the characteristics of hot-formed springs, we use springs that are wound cold and cannot be changed. When they reach the end of their life, they’re done and are not suited for reclamation except through scrapping.

It’s important to get all the performance a spring has to offer since there’s no way of adding life at the end. Scragging normally does that; however, in the case of the spring inside a spring-piston air rifle, the scragging process can occur naturally during operation since the spring is nearly coil-bound every time it’s cocked. So, scragging doesn’t really add life to an airgun spring.

What it does is make the spring shorter so it’s easier to stuff inside the powerplant. But if you don’t want to do it and can get the spring into the gun anyway, you can either cock the rifle and leave it cocked for about four hours or else you can just use the gun normally and the scragging will take care of itself over time.

One final thought
Manufacturing being the imprecise process that it is, every airgun powerplant will have slightly different dimensions — even within identical models. So, the length of the spring that fits inside the powerplant will change from one gun to the next. That’s why manufactured airguns cannot be held to tolerances as close as those that are tuned by hand. Some of the “slop” we see in off-the-shelf spring-piston guns is there to account for these small differences. That’s why an individually tuned gun can usually be made smoother and more powerful than one made by a factory process.

82 thoughts on “Resizing a mainspring”

  1. Interesting term, “scragging”. I wonder who came up with that and why… I can see why it would be a useful process, but why call “setting” scragging?


  2. A picture is worth a thousand words, (even if they are very strange words). Thanks, BB. You do such a nice job of explaining, and the photos are so well done. You are quite the photographer (or is it Edith?).

    • Jerry,

      I’m the photographer. This subject isn’t easy to explain, which is why the pictures are there. I don’t think a lot of air gunners appreciate what a spring has to do inside their gun. This shows it more clearly.


  3. A question for you knowledgeable folks. I recently bought my first spring-piston airgun (Diana LP-8), and in the owners manual it suggests lubricating the piston after 1000 shots. Will I need to dismantle part of the spring-piston assembly to accomplish this? There is a drawing in the manual with an arrow to show where to lube it, but I can’t make sense of it. Thanks, RC

    • RC,

      In the first place you probably don’t need to lubricate the piston of your gun. Unless it honks like a goose when you cock it, your gun probably has all the lubricant it requires.

      But when the time does come, you put a drop- or two of silicone chamber oil down into the air transfer port and let it get into the compression chamber by gravity. No disassembly is required.

      When you cock the gun the air transfer port is the hole in the mainspring tub that is immediately behind tyne barrel. When the barrel is broken open, you can see it.

      Her is a three-part report I did on your pistol:



  4. Hi B.B.,

    I’m going to be purchasing the Eun Jin Sumatra .25 500cc in the beginning of May, and was hoping you’ll be able to do a review on it soon, or when you get the time.


  5. B.B.

    Great and very useful article!

    It’s good illustration why shooting gas-springer accurately is a bit easier than shooting steel-springer – gas springs do not kink and give the gun less lateral vibrations.

    Maybe that’s a subject for your next article so please forgive me for interrupting with my own observations 🙂

    I would also mention that steel springs are expendable – their active service life lies most times between 3000 and 5000 shots, then they loose their quality due to “fatigue” and they have to be replaced.

    The farther a spring’s working conditions are from coilbound – the more it “lives”, however the less power one can squeese from it in given cylinder. So, constructing or tuning one is always trying to twist the equation “spring force – preload – lifetime – wire diameter- compressed/uncompressed lengths” to his advantage. Sometimes a very thick wire and “hot” spring working under rather relaxed preload and compression conditions is equal in resulting power output to thiner wire spring working under significant stress at the price of its lifetime.

    There’s no direct correlation between the force of the spring and its service life, but I noticed, that thicker wire spring require more attention before installing them and they seem (just an unproved feeling) to be more prone to breaking under loads towards the end of their lifecycle. Maybe that has connection to R. Beeman’s observation in the means of “more strands – more defects”. I know that Soviet Olympic springers as well as aircraft MGs had “braided” mainsprings and they have a reputation of “undying” – maybe that’s a solution for a thicker wire.

    One thing to make a spring to work its complete lifecycle is a good seal and correct cylinder/barrel bypass diameter (I’ve got the table somewhere on my computer with optimums for each cylinder volume/spring force proportion). In effective-working cylinder air cushion prevents the spring from hitting the front end too hard thus extending its lifetime by moderating stresses.


    • Sorry, just forgot that. I myself use a similar scragging tool, that also works as an assembly compressor. The only difference is that it’s two rods and steel bars between them and fly nuts instead of wrenches.

      • B.B.

        So I wonder why airgun makers don’t use them – production cost, profits from selling spare springs or, maybe, dimensions/force problem? I think I must dig some info from my side, as braided springs look interesting.


        • B.B.

          Well, excavations brought some results – no magic, no conspiracy either. A single-wire spring has a serious advantage over braided spring of the same dimensions – it is stiffer and gives more force, which is important for springer powerplant. So, theoretically it is possible to use braided springs in airguns, however at the cost of dimensions, weight and efficiency.
          Braided springs provide “softer” and less force and are more suitable as e.g. recoil compensators, having longer lifetime and much more constant tension over time. They give out force in less “explosive” way, which means they are less efficient as a power behind the piston.


          • duskwight,

            Thank you for doing the research! Now we know something more about coiled springs.

            The springs I saw that were braided were so strong that I couldn’t have measured if they were weaker than a one-wire spring of the same size or not. They had hundreds of pounds of force, because they were indeed the recoil springs of a 20 mm automatic cannon. So your research is very useful.

            Thank you,


            • This thread is absolutely fascinating. And, of course it makes perfect sense, the spring will “stack” coil on coil like a stack of pennies, when it’s fully compressed.

  6. I’m not a spring gun tuner and don’t play one on TV.

    Using this home made device appears to effectively pre-set a spring while at the same time introducing cant in a new spring. Is this true? Tuners?


  7. HAPPY, HAPPY, HAPPY…oh yes I are happy.
    My plumbing issue ended up having a very reasonable ending.
    Instead of a broken sewer under the basement it was roots in the pipe…a good roto-rooting and the problem was solved. Wasn’t exactly cheap (I have a long backyard with a lot of pipe to clear) but way cheaper than even the ‘best case scenario’ from Saturdays estimate.
    And….my PAL arrived in the mail (what you need in Canada to possess a firearm or air rifle over 500fps.
    So tonight the Savage .22WMR I purchased before Christmas (and stored at a licensed friends house) comes home to roost.
    And I think there will be just enough $$ this summer to get that HW97K (the blue laminate one).
    Ahhh…life is good.

    • Wow, CSD. It’s barely lunchtime, and you’ve had quite a good day already! Watch out for falling anvils.

      Folks, I have zero spring-powered guns, but I just love hearing about them, and all the heroics it takes just to keep ’em running, and to have some hope of putting rounds on target. Such a noble sort of masochism.


      • Matt, I hope to get out shooting this weekend.
        Only problem is we had a couple of very heavy snowfalls two weeks ago…followed by unseasonably warm weather the last week…the range will be a mudhole.

    • CSD,

      Lots of good news.

      Glad to hear your sewage pipe problem was just tree roots. What did you use to treat the roots inside your sewer pipe now that they’re freshly cut?


      • The plumber recommended something called Root-X, which he claims (and the ‘net seems to confirm) will greatly slow down the growth of the roots.
        I’ll give it a try. His other option was to cut down the trees but that will be a last resort. I have a great backyard, and part of what makes it so is the plum, crab-apple and lilac trees…without them it just a big patch of grass.

        • csd,

          Root-X is the stuff I use. Swear by it. Use it soon beofre the root can heal and when you’re entire family will be gone for awhile. Longer the better so you don’t rinse it off.


  8. I knew you could break a spring from stretching, but can you do so from compressing? I thought the coil-bound state would prevent breakage. Maybe it has to do with the stiffness of the spring.

    Good news. I’ve been in something of a slump, even though slumps don’t exist and every shot is an independent event. I think partly it’s because I have been so distracted with work that I haven’t had time to visualize my shooting sequence as I often do. Shooting is confined to just my time shooting. Also, there has been a bit of eyestrain. But whatever the reason, I have been flinching shots downward. A half inch at 20 feet is pretty significant. And this is something that bedeviled me in my miserable high school shooting career. Actually, I’m fairly pleased that I did not panic like the old days. I reflected on the method, made the right adjustment, and last night I was back in form. 🙂

    On the other hand, CowBoyStar Dad, I think I am bearing a Karma shift behind your good fortune. Last night I received a piece of mail with one end slit off the envelope. Inside was my social security number and all sorts of other information. Argh. I’ve heard about identity theft, but never imagined it happening to me–especially when it’s not my fault! In reading around, it looks like there is no way to get the cat back in the bag. The best you can do is monitor credit reports and call the IRS and Social Security to try to be alert to problems and maintain an active defense. Flobert, maybe there’s something to being off the grid. Well, the rain falls alike on the just and the unjust.

    Victor, didn’t you do Shotokan Karate? Did your school look like this?


    Ow. I notice a lot of people getting popped in the face. Are they neglecting some guard? Or is the philosophy to cast aside all defense and stake everything on an attack? That is a persistent school of thought I know. I know that boxing has extensive measures against just this sort of thing including chin down, shoulder up, catching, parrying, knifing off the counter punch, slipping, bobbing and weaving and sidestepping. Now this resonated with me and was something I was motivated to learn! As another sign of temperamental preference, I remember one Karate sparring match where the opponent launched a screaming surprise attack with a jumping front kick which bulldozed me into a wall. Then, he unleashed a furious barrage of punches and kicks as I covered up. I must have looked pathetic, but in the midst of all this, I was suddenly overcome by a laughing jag! The screaming attack just seemed like a caricature and ridiculous. I covered up until it was over and wasn’t really hurt. Anyway, Karate has far too old a tradition and an eminent record to dismiss, and there is much that is very interesting and makes sense. But the business of walking into punches into your face I just do not get.


    • Matt – I have essentially two “off the grid mentors”. One is a guy, D., who had his ID stolen sometime around the year 2000 I’ll guess, and apparently it had nearly ruined him. When I met him, he was the picture of frugality, did everything cash, not poor necessarily but VERY VERY careful. For instance, he researched buying a car extensively, bought a Toyota from a rental-car fleet, and when I saw him a week ago, told me his Toyota now has over 200k on the odometer, still going strong. He does not keep a computer in his house, does everything cash that he can do, I believe banks with a credit union if he banks at all, only uses computers at places other than his house, and only for ham-radio related stuff (he “deals” a lot in QSL cards). While he lives fairly normally, he essentially has “one foot in the lifeboat” where if he becomes a non-person again, he’s prepared for it.

      The other guy, A., plays music on the street and rather well. But to him, his crowning achievement is a fat, softbound book he’s written and is always pushing, all about the Illuminati, the Bildersburgers, etc yadda yadda. Naturally he believes in the Beast, the Number Of The Beast, and the whole nine yards. Thus, in his belief system, he’s the Beast’s enemy and since the Beast is embodied in all the info-networks kept on everyone (and with this last I don’t disagree), he naturally has to stay off the grid. He traveled by Greyhound until a few years ago when he finally got a car, I think kept in someone else’s name. I don’t think he deals with banks at all, in fact neither of these guys use credit cards, or any of that BS. I’ve never seen D. use a cell phone, and A. may have one but I’ve never seen him with one either.

      The thing is, when the economy went into its ongoing collapse, it was at most a minor change of gears for these folks. I used to think A. was a real wingnut. But in this “new economy” these guys are the smartest guys in the room, with kooky ol’ A. coming out on top. Playing music on the street means undocumented income, hidden from Big Brother, and it also means some goodwill among the public, and you gotta have friends on the street.

      On the karate, I’m gonna make a mean comment and say, Boxing has all these defenses because boxing punches can hurt ya? Ba-da, boom! I’m here all week.

    • Matt – I’m gonna enlarge a bit here. I’m not really off the grid. I have a cell phone, a car, a driver’s license, email address, and an actual account holding about $20 in a credit union. That’s not off the grid.

      But I don’t use credit cards or a debit card, my cell phone is a pay-as-you-go phone (which I’ve found is the favored model among 80-year-old Filipino guys who ride the bus lol) and I do all things I possibly can, face to face and cash. I pay no rent where I live, do gardening and chores and stuff, raise my own eggs, etc.

      I describe my life now as “one foot in the lifeboat”. I know how quickly a person can lose everything. I’ve got my bicycle and food stores and skills and most importantly, friends. I cultivate many different ways of making a few dollars, and live fairly well on what most people would consider grinding poverty. Back in 2008, I was going MONTHS without income, or maybe I’d make $5, all month. Things were a bit better in 2009, then in 2010 I sold my motorcycle because I could not afford to keep a 250cc in gas. In 2010 I made very little, but I also started learning about recycling, casual labor, etc. 2011 was actually fairly decent, in my terms anyway, still below the “poverty line” for an individual in 2009, the latest figures The Internet has.

      I’ll get a job and it will last 2 months, then something else will show up….. I always have about 5-6 things going. And I know the plants and stuff around here pretty well too, and trapping etc.

      Right now, I have some work building circuit boards. TINY SMT components, and amazingly I’m doing ’em OK. LIke those guys who got out of electronics when transistors came in, I didn’t want anything to do with SMT stuff, so I’m a newb learning to work with them now. This may amount to some work, or it may peter out in 6 weeks. Or in 3 weeks. It doesn’t really matter, because I’ve become very adaptable.

      Losing everything isn’t a matter of If, just a matter of When. So, start building your lifeboat now.

      • Flobert

        Good approach.
        I always try to stick to the rule – “no money except for those you can hold in your hand”. This means no cards, no legalized robbery (sorry, I meant credits 🙂 ), no mortgage and so on. Always trying to do things face to face and come to light as little as possible ,which means as little involvement in state paperwork as possible. And yes, I have multiple undocumented income sources and cellphones registered on other people. I’m not paranoid, I just feel myself safer, more private and more comfortable this way. “Off the grid” and “out of the bubble economy” rules.


        • A while back I was at my credit union and got some money out from a check I’d deposited, the last one from an electronics job actually. I had some 20’s I wanted to exchange for a $100. The way the credit union does it, and maybe all banks now, is, they treat it as a deposit and then a withdrawal. The effect was to add a paper trail to that $100. I will never ask them to change a bill or bills again.

          Big Brother/The Beast/etc hates cash. Ideally, everyone has something like a debit/ID/political affiliation/we-gave-at-the-office card, keyed to an implant that can’t be removed w/o endangering life. Every activity, transaction, location, etc is traced and goes into a hee-yuge gov’t database. People can already be declared terrorists for any reason or no reason at all, but ideally the whole process becomes perfectly documented, so with data-mining the huge octopus of gov’t can tell who might be dangerous 10 years from now and order a drone strike on ’em now. They hate the idea of freedom of assembly, freedom of speech and expression, all that Constutional stuff. And cash, esp. copper, gold, silver, the money of the people, really scares them the most. What we’re rapidly progressing to is something like the old USSR, everything State-owned including the people.

          But like the old USSR, there will be a thriving criminal and underground economy. You can already read of things like places where the food laws are extremely restrictive, “farm to table” parties being raided, places where hand-offs of cash for lobster sandwiches occur on the street, etc. Think about it: the largest “sector” of crime these days is actually transactions such as for drugs, foods, herbs, things like guns, that the Gov’t wants to control and can’t, so a person can be declared a felon/terrorist for some pretty mild stuff. Violent crime is actually down and has been going down for years. These transactions are always in cash or various barter items. I’ve heard of herb-for-tractor deals. The gov’t hates that! (Just a footnote: My own vices are all bland, routine, gov’t approved stuff. Got no use for the herb, personally. Alcohol and coffee are my weaknesses.)

          • Last time I was at a CU to exchange money it was NOT treated as a deposit followed by a withdrawal.

            What WAS tracked, on paper, was the /type/ of money going into and out of the cash drawer. I suspect that, at the end of the day, if the bills didn’t match in quantity what the computer said went in and out, the cashier might have some explaining to do — even if the monetary total were correct.

            • The gal at my CU actually did the papers for a deposit and a withdrawal, maybe that’s their way of keeping track I dunno but I don’t like it.

              “one foot in the lifeboat” is a good way to live.

    • Matt61,

      Good Lord!!! That is horrible stuff! No, I did not study Shotokan. Our style was much more sophisticated, and defense was a critical element of it. There was no single stance, or posture for fighting. How you fought depended on your opponent. For instance, if short and facing a tall opponent, you take a very low stance (very hard to do in a real fight unless you are highly trained). You made your opponent reach, exposing weakness. When upright, our stances weren’t very different from a boxers, except for an open extended hand. Outright attacks were with balance between both legs, with legs just within shoulder width for maximum power. We typically deflected the punches, forcing the opponent to lose against his own energy. We VERY rarely threw high kicks, as our kicks were more like straight punches, making them quicker, harder to block (a smaller cross-section), and generally more effective. Our style preferred opponents who did round-house, spin, jump, and high kicks. Because of our focus, those types of kicks took to long, and so were effectively slow for us. Our style was entirely about being super efficient, quick, and powerful. The path to perfect kumite was form. Strict requirements on kata is the only way to truly do this. Kata is where most dojo’s cut corners, unfortunately. Also, we did a lot of grabbing, so sloppy opponents tended to suffer a great deal. We also did a lot of side-step and counters to deal with heavy charges. Very clean and effective, IF you practice for that.


      • One last thing. Our style was NOT recreational. It was deadly serious, which is why we had such a high attrition rate. It could never be done as a business. It’s been tried by ex-students, and always fails. The demands are simply way to high for the vast majority of paying customers. Few want to pay to be pushed so hard.

    • Matt,

      This looks like “point” fighting tournements to me. It’s intense because the only point scored is the first one executed with “perfect” technique or a knockout/tko. It’s not continous like a boxing match or continous sparring where you can let your opponent wear themselves out. They give everything to the first 10 seconds of the fight and then have nothing left, which in many real situations can be costly. We fought continous for 2 minute rounds, with or without pads, not stopping to admire our work after 1 or 2 successful techniques. That would get you nothing but pain.


      • Yes. Perfect form must be the requirement, and a single such strike ends with a point. However, defense must also be perfected, so it should also be VERY difficult to score. So you must also be good at forcing your opponent into making mistakes. I would imagine that the requirements are like fencing. And, yes, no gloves, or thin cloth pads. While training, my wife once hit me dead between the eyes, leaving a checkered imprint that lasted a few days.

        • Exactly! It was hilarious! Next day I was out of town at a conference, and found people that I was talking to staring at my forehead, just above and between my eyes. My wife was training for a tournament, and we were practicing body shots, but I deflected a punch up into my face. She hits pretty hard, as everyone could tell. 🙂

  9. BB,
    I think you wrote all that just so you could use the term “scragging” :). As you say, it really does nothing except make the spring shorter and easier to install. I’ve been thinking about making a coil spring for fun, as I’ve made some small “flat” and “vee” type springs and they all come out pretty well. I would think coil springs are wound cold and then heated, quenched and tempered, as flat springs are but you seem to indicate airgun springs are not heat treated after winding? Just curious, and wondering if it wouldn’t be a way to revitalize or rev up a soggy spring.

  10. Lovely article (as usual) BB.
    A few things that i have noticed after scragging.
    1. The rifle is softer to cock.
    2. the performance seems to have improved and also shoots consistently.
    I might be wrong on these as i have no data to back it up but i’m pretty sure it happens.

    Did you by any chance measure the FPS & cocking effort before and after scragging – if no would it be possible for you to check and please post results for us.

    Thank you BB.

  11. An ideal air rifle spring would be of rectangular “coil section”, 3 times as deep down the length of the spring as it is around the spring, that is to say rectangular 3×1 bar placed wide side against the lathe as it turns and then coiled to a spring spaced so that it compresses 1/3 its length when at the final “shooting” or “cocked” position, just off of being coil bound, but only 5mm longer than the chamber into which it is to fit, thus never being massively compressed when stood, it will lose little or no energy over time or per shot, as such custom springs can be guaranteed for a million cycles it NEVER needs replacing, obviously finished with the flat base at each end too…

    You’ll find the rifle has far greater power and remains as effective as the day the spring is put in until the day you effectively part with it as they place you in a coffin… it having JUST enough of a few millimeters over-sizing to prevent rattling when fired.

    • spadge,

      I removed your comments that were insulting. This blog is read by families, so we keep the language clean and the discussions civil here. No one ever gets flamed.

      If you can live with that, welcome to the blog.


  12. Your best bet for such springs is to look into independent spring manufacturers for a single custom spring, many have even got design your own spring apps nowadays, and they are not a fortune, often £50 or £60 including P&P. As gun shops tend to sell cheap round-coil springs, over-sized, poorly designed and literally designed for return market and to need replacing, not designed to last and give performance for your money.

  13. My opinion: if it wasn’t for the return market scammers, the air rifle is the pinnacle of weapons design, particularly for pest control.

    For vermin control, its cheaper per shot, its safer than a high velocity that can ricochet and come down a mile away unpredictably even with the heavier shot weight, so safer by far and if made right would pay for itself over and over “in a season”. It is merely ridiculous legislation that limits them to being barely toys rather than the deadly weapon and tool they could be and return market that makes it more costly than the pellets alone.

    As for the legislation, that again is more about money than actual safety… and it is obvious to see it too. In fact ANY moron can see it. A better system would be a “hard air” category, possibly postcode legislated, definitely licensed for a minimal fee, preferably to over 21’s only, but those who own gun-shops would rather force to high-velocity at £1.00 to £1.50 per shot, requiring powder and explosives that are then a ridiculous leap of risk… where a shot can hit a stone and come down over a mile away. It is nothing short of a farce.

    • Don,

      You are on the world’s most active shooting sports blog. Yes, it’s still active. There are hundreds of blog topics for you.

      Over the years I have tuned dozens of spring guns. Most recently I tuned a Diana 45.


      Welcome to the blog.


  14. Great post, my question is with a lot of people saying there is around 1000 shots before a new spring “settles in”, does scragging a new spring for 4 hours eliminate / reduce this “settling in” period and allow for better performance, sooner?

    Also, if I am planning to reduce a new springs length due to adding a short stroke extension to the piston, is scragging a good idea to shorten a spring before removing any coils?

    Sorry if any of this was covered previously…

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