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Education / Training Spring gun tuning: Part 1

Spring gun tuning: Part 1

by B.B. Pelletier

Before we begin, let me announce that the last of the British-made Webley airguns are now in! Pyramyd AIR bought the entire remaining stock of guns, so look through the Webley pages now. When these are gone, there won’t be any more!

I’m going to show you the fundamental steps to tune a spring gun. Although I won’t show every kind of gun, I will talk about how underlevers and sidelevers differ from breakbarrels. If you’re clever enough to do this kind of work, you’ll be able to figure out the particulars for yourself. I’m just going to show you the important points to get you started.

We’ll begin by looking at the tools and supplies needed to work on spring guns. I assume you have a standard set of tools and all the screwdrivers and Allen wrenches you need for any job. If you don’t have them all now, get them as you need them. Never try to make one tool do the job of another – that’s how accidents happen and mistakes are made.

Pin punches
You need a good set of these, because there are hundreds of uses for them when working on spring guns. We will use them from the beginning, so get a small set of punches right away. Airgunsmiths need small punches, because most of the pins encountered are small. I bought my set at Sears, and it has four punches – 1/16″, 3/32″, 1/8″, 5/32″, plus a 5/32″ alignment tool.

Plastic and rubber-headed hammer
This is also a general tool that’s used all the time. Get one that’s small and handy to use. This kind of hammer is essential. You can buy one at Sears or Home Depot; if you like shopping on internet, try Boston Industrial. They have one for $2.10.

A hammer with rubber and plastic heads is an essential tool for the airgunsmith.

A vice
Vices are not as useful as you might think. Spring gun tuners have very little need for vices, save one. A fine, inexpensive mainspring compressor can be made with the right kind of vice. I will give you the plans for how to build a compressor, and I’ll also tell you where to buy one if you don’t want to build it.

Dowel rods and rubber bands
Get at least one half-inch hardwood dowel. You’ll use it to lubricate the mainspring cylinder. If you have a screwdriver with an 18″ long blade, it can take the place of the dowel. Also, get a supply of thin rubber bands, to use with the dowel. I will explain what to do when we get there. A dowel 36″ long is more than enough. All you need for most jobs is about 18″.

Lubricants are a major part of a spring-piston tuner’s bag of tricks. Ten years ago, the market had the products you needed and they were easy to find. For example, Beeman sold M-2-M moly paste that was wonderful stuff. Well, they don’t sell it anymore, so you now have to buy your lubricants elsewhere. I want you to at least get black tar and moly paste. I’m sending you to Air Rifle Headquarters for these things. They are also an excellent source for replacement mainsprings, piston seals, spring guides and other important parts you will need to tune a gun. They have already created drop-in tuning kits for many popular spring rifles like the Benjamin Legacy and the FWB 124/127. So, this is a place you aspiring tuners need to bookmark.

Next time we’ll look at mainspring compressors, and I’ll show you how to make one for less than $20.

49 thoughts on “Spring gun tuning: Part 1”

  1. B.B.

    This is off topic for the tuning thing but I have to ask you a question. I’m want to get a gamo cf-x and a scope. The scope I was wanting was the leapers 5th gen 6-24×50. I was wondering, would this scope work and what mount should I get for it. Thanks for any help.


  2. I’d like to correct that post. I don’t think that scope is one of the 5th gens but I’m not sure. It is this scope.


    Thanks again,


  3. mr-lama,

    I own one of these Leapers 6-24 scopes and I just put it next to my CF-X. It will overhang the rotating breech, which many shooters find disturbing. That’s why I used a Leapers Compact scope in the field test.

    B.B. and

  4. So will the fact that it overhangs the breech actually be a problem in loading? And will this scope have any problem with the recoil of the Cf-x? Also, will I need any special mounts to handle this big scope. Thanks


  5. B.B.
    When you practice shooting air pistols at home, what is your favorite pistol to shoot? Which type do you prefer for pistols when target practicing? (spring?, single stroke pneumatic?, etc…)

  6. Yes it would, I would love this scope on a cf-x. I actually placed an order with this scope/gun combination but pyramyd air sent me something about how the scope won’t work on the gun. I couldn’t figure out why. I figured I’d ask B.B. I thought maybe there was a problem with the mount but again I’m not sure. So B.B. if you could give me a list of a few mounts that would work, that would be great. I would hate not to have these two together.

  7. mr-lama,

    Piramyd Air was correct in trying to not sell you this scope. I have used overhanging scopes on underlevers like the CF-X, but I use them with high mounts and I don’t mind the tight squeeze. I think most shooters would not like it.

    As for handling the recoil, no problem. The CF-X is a pussycat in the recoil department and Leapers scopes are among the toughest made. That doesn’t mean you can’t get a bad one, but I never have and I’ve tested more than 50 of them. Compared to the old Tascos that broke when you looked at them (the Tasco Prohunter series) Leapers scopes are bulletproof.

    If you have to get this scope, I recommend high two-piece rings for the extra adaptability.


  8. mr-lama,

    The 6-24 has a one-inch tube. I know you want to know that to select the mounts, but you can ask the sales people at Pyramyd AIR, too. I say that because it sounds like you have spoken to them already.

    Also, Leapers has a website where there is even more technical information http://www.leapers.com

    Having said all that, I just went to the Leapers site and the tube diameter isn’t given anywhere! Wow! Well, I have one and it has a one inch tube. Ask Pyramyd AIR to check it before shipping, because the rings have to match the tube.


  9. Yeah, the leapers website really doesn’t say much about the scope at all. Oh well, I’ll call and check on it. I’ll let you know how it works out. Thanks a bunch,


  10. Question on Leapers scopes and magnum recoil like from an RWS 52.

    According to the testing article by Tom Gaylord, the Leapers scope held up well to a Patriot’s recoil.

    What concerns me more is how these scopes will hold up after 100, 200, 1000, 5000 shots.

    Any data on this issue?

    I love the features of these scopes but I would prefer not to have it for a month and have it fall apart on me.

    thank you in advance

  11. Lawrence,

    I own several Leapers scopes that must have 5,000 shots on them. The problem with a guy like me who tests a lot of airguns is I’m always moving scopes from one gun to another. That can be just as damaging as the recoil from a magnum gun.

    I read Tom’s report on the TS scope and he shot it in excess of 800 shots during that test. For a Patriot, that is a lot of shots. I don’t know many Patriot owners who shoot more than that in a year, unless it’s their only gun.

    I will not say that a Leapers scope will never fail, because I read reports of their failure on the airgun forums. But there are reports of other scopes failing, too.

    All I can say is that in my own experience, Leapers scopes are very tough.


  12. B.B.
    I just received my RWS 350 magnum and my buddy his RWS 52. After some initial pain and suffering (without any reason) we started hitting the 10 ring. Both are great guns and we finally started nailing the ground squirrels that are over-running my almond orchard. We each pulled off some remarkable shots of 80+ yards. I had no idea that was possible with an airgun, but I’m new to this, so I’m amazed. Looking forward to this post on tuning the guns.

    One question or comment: You have previously stated that some ammo works better in some guns than in other guns. Both of our guns shot the Crossman Premiers and JSB Predator extemely well and the Gamo Master Point pretty darn goo. But other “quality” pellets shot wildly (by 3-4″ at 25 yrds). The Beeman Crow Magnum and Silver Arrow were terrible in our guns. I thought there would be some difference, but not 3 or 4 inches at 25 yards. Does this sound right? Could there be that much difference? Also, when a pellet doesn’t quite fit right or maybe goes in the barrell slightly crooked, does this affect the accuracy of the shot?

    Thanks for the info and help!


  13. Chazer:

    In my experience both Crow Magnums and Silver Arrows are inaccurate in any gun I have tried them in. Premiers are accurate. The JSB Exacts are accurate. In general I find domed pellets the best. Good quality wadcutters are wonderfully accurate but have a lot of drag and little penetration. They are excellent for hunting at shorter distances however as they have a lot of knock down power.

    I have had mixed experiences with the JSB Penetrator pellets, but they sure are neat aren’t they? It’s great to hear that they are working for you.

    I don’t think there is any way to put a pellet in crooked unless it isn’t fully seated. Once the skirt is seated flush the pellet will be lined up nicely. Sometimes a pellet feels like it is going in wrong. I find that if I take it out and try again it will usually line up fine. If this happens more than once I would toss it, although I haven’t had this problem.


  14. Lama,

    regarding the cool scope you’d like to put on a CFx. if i read right the scope you want is the 6-24×50 varmint killer which measures 370mm. That’s 14.66+ inches not counting the got to have flip open covers. DON’T DO IT!!!

    i have a CFx with a Leapers 3-12×44 full size scope which is only 12+ inches. and while it does look cool it’s just on the other side of user friendly for the CFx. the eye end was about 1/2 to 3/4 inch too far back for easy eye alignment. Oh, and you will probably have to remove the rear site, as it was in the way of the flip lense. I never tried high mount rings and that could help alot like BB has said. I don’t like scopes mounted too high for cheek to stock reasons for me. also make sure you get the optional big A O wheel, that will work and fit great.
    I put a mini scope with the same specs (3-12×44 a o) on and it’s night and day in the user friendly dept! It doesn’t look as cool, but it works better.

    The CFx is hard enough to shoot with consitant accuracy as it is, (real perticular how and where you hold it)but the longer scope I had just added to the finicky behavior. I also mounted a swivel on the underlever arm bracket so I can use a bipod or a sling. the sling changes the way the CFx shoots if you use it for support around your arm in ANY configuration, so I prefer the bipod.

    That’s my 2 cents anyway.

    happy shooting


  15. the call it “tar”. does this mean that it is so think, it will slow down velocity?
    blah. i’ll never get my hands on it here.
    worse yet, there is no airgun smith that i know of, so i have to do all repairs/tunes on my own. that makes me nervous. esp. the mainspring. i’ve heard my fair share of horror stories of a spring with lots of preload that ricochets around their walls.

  16. I hate to monopolize your time so feel free to tell me you’re too busy.

    Straight up, I’d like your recommendation for scopes/mounts for my RWS 52.

    I realize this is subjective and there is no one right answer, but I am soliciting lots of suggestions and look forward to yours.


  17. dsw,

    I can kind of see what your saying, especially with how long the scope is. I think I will go ahead and order it, just to try it out for myself. If it doesn’t work I have plenty of firearms that need scoping and I’ll go buy a compact for my cf-x. Also, how did you mount a swivel (and what/where did you get the swivel) on the underlever. I would love to put a bipod on mine but I didn’t know that it was possible. Thanks,


  18. Lawrence,

    May I suggest a couple of scopes? I got a Leapers 4-16×50 illuminated mil dot. Works great and is plenty bright. It was about $100. My friend wanted to try out something else so he bought a BSA AR 3-12X50mm with Adjustable Objective. It ran him about $90. Both worked well after sorting out the initial problems. When we did our jobs, the scope and guns did theirs.

    Thanks for the feed back. After reading more on this sight, I found that it may have been the weight of the pellet that was throwing the POI so high and to the right for those Silver Arrows. I just ordered a bunch of 14-16 gr. pellets thinking that is the weight that will work best for my 350. Anything heavier either “flew” of dived straight down. I sometimes shoot my .223 Ruger and I know I’m a better shot than I was getting. So, we’ll see and test with the new pellets I have coming. Yeah, the Predator was good and it looks cool. What more can you ask? Still the Premiers were deadly.

    Sometimes the pellets just don’t seem to seat correctly. Rather than ruin the chamber, I just close the barrel and hope for the best. Maybe that’s quality control as it didn’t happen with the two that shot the best for me… hmmm.

    I just can’t see how my palm would be better than a nice sand bag… Maybe someone can fill me in on that one.


  19. Lawrence,

    For a 52 I’d suggest the Leapers 3 to 12 Tactical compact scope I used to test the CF-X. It’s sized just right for a sidelever where you need access to load the pellet. The B-Square rings I used are also great.


  20. Chazer:

    I agree, sandbag v. palm doesn’t make sense, but it is true that the gun will work best loosely held and just rested on your open palm. Spring air rifles are just odd this way. They like to bounce around in your hands. If allowed to bounce around exactly the same way each time they are very accurate. Weird, huh? My guess as to sandbags is that they don’t let the rifle move the same each time with the sand shifting, etc. Sandbags sure work great with a firearms however.

    With respect to pellets, I find that it is easiest to find a pellet that works well in a particular gun and to stick with it and learn its characteristics. Air guns have a trajectory that occurs over a relatively short distance because of the low velocity of the pellets v. a bullet (a .223 is a very flat high speed round that one can sight in for a fairly long distance and almost ignore trajectory for most purposes).

    I suggest you zero your air rifle at around 20 to 25 yards (closer for a heavier/slower pellet) and then check how high or low your shots hit at various distances up to the longest yardage you expect to shoot. If your zero distance is right you will get a nice “long” (maybe ten yards) plateau where the shot is just a little low or high as the pellet is in the middle of the trajectory. This is the sweet spot for your particular rifle/ pellet combination. Hitting anything at this middle distance is pretty straight forward. Longer distances require a bit more thought as you then have to hold a little high. It is frustrating at first been then really cool once you get it figured out. It is actually part of the fun.

    My current silliness is to shoot a Feinwerkbau 700 match rifle outside at 30 feet or so to shoot the stems of dandelions so that the head falls off. It is amazingly amusing on a pretty day to practice precision shooting this way (along with cutting down tall grass stalks at a distance). It actually improves my ten meter target shooting. A match rifle is also a wonderful way to hunt squirrels if you are willing to be patient enough to get close and to set up a perfect shot. At only 5 ft/lbs. of energy the shot has got to be flawless. If it won’t be, don’t take it. It is a wonderful challenge. (Carrying a ten pound plus match rifle around is another challenge – great exercise).


  21. Ehrich,

    Thanks again for the latest insight. I plan to “zero” my gun next chance I have. It’s hitting dimes or better (ahem, with my sandbag) at 20-25 yards. From there I’ll march off 5 or 10 yard distances and test how much drop I incur. I think the big help will be to chart it all for a quick reference. I took several pokes at some squirrels from 75 yds (at least that’s what I stepped off) and I had to shoot above them about 1 foot, I think. Not very scientific, yet. Does this all sound right? And how can a palm be as steady as a solid object, especially shooting at 16 power at an 89yrd target???

    When the squirrels are gone… I’ll take up that dandelion shooting. Lord knows I’ll have enough pellets to practice with. I ordered every 14-16 grain pell that Pyramyd has for sale!


  22. Chazer:

    Fun report!

    Dime size groups at 20-25 yards are great! The sandbag is working for you and for your gun. I wouldn’t change a thing with results like this. That’s within a couple of minutes of accuracy. Cool!

    A sandbag is a lot more steady than at least my palm, that’s for sure. It isn’t an issue of steadiness, it’s just how spring air guns typically like to be held. You obviously found a great way to shoot your gun. Go with it! It sounds like you are having a blast.

    Your plan to measure off distances and measure drop is excellent. The drop is pretty quick so I would go with five yard increments as you can never have too much data. A foot over at 75 yards sounds about right.

    I, too, like buying pellets. I’ve got many more than I likely will ever use. Too many rounds of firearm ammunition and other such goodies, too. This stuff is just inherently cool. 🙂

    Good shooting!


  23. Thanks for the tips, Ehrich. I’ll start at 5 yard increments and chart away. Now, if I can only quit this job so I can find the time, I’ll be golden…



  24. I haven’t seen or used the Gel Support that you identified. It looks like a great idea however. I think an open palm works because of its repeatability. The Gel Support appears to offer the same advantage.

    Maybe B.B. or someone else has used one and can tell us.


  25. Has anyone tried those gel-pad mouse pads? It has a gel pad for your wrist. I have one around the office here somewhere. I’m going to try it if I can find one. If that seems to have some potential, I’ll order the pad from Pyramydair. It seems like a small enough product to stick in my pocket while I roam the orchard hunting the squirrely rascals..


  26. BB,

    I this article you mentoned the tools needed for working on a spring powered airgun. I like to know what set of tools I need to work on a Pneumatic airgun and a PCP air rifle?


  27. Joe,

    To work on PCPs and pneumatics you need special spanners to unscrew valves set deep in the rifle. Also you need an endless supply of fittings, hoses, gauges and clamps. And a chronograph is the single most important tool.


  28. BB,

    Thanks for you info.
    Where can I buy these special spanners ?
    Why do I need “endless supply of fittings, hoses, gauges and clamps.”?
    Is there a book on how to repair pnuematic airguns?


  29. Joe,

    There is no PCP repair book, but some Brits did write a book on how to build a PCP. It’s self-published and printed on a home printer.

    Contact Brian & Associates and see if they have a copy. Or try Doug Law. Google both.

    As for the tools, you make them as you go.


  30. BB,

    I have a fine Leapers scope that has a problem with a jumping reticle; in other words, it won’t group. It is EVERYWHERE and it has the allen-screwed lok-tite mount with NO wiggle at all. Where can I send it for repair?

    Thanks for your great column.


  31. Dan,

    Two things come to mind when I read your problem. Either the scope is adjusted too high and the erector tube is bouncing around or the scope may be broken.

    As long as you are careful about head placement for a repeatable eye location, those are the only two things I can think of that will cause your problem.


  32. BB,

    Thanks as always for your fast reply. When you say “adjusted too high” are you refering to the elevation screw being maxed out or close to it? That is not the case if that is your meaning; great thought though. I think the scope is just shot. Is there someone who you would recommend to repair it?



  33. Anonymous Squirrel killer

    If you are talking about the Nitrogen gas spring, the big benefit is that it can be left cocked indefinitely. A metal spring would "take a set" if left compressed for so long, and would lose power.

    They are supposed to last longer than a metal spring would as well. The gun will still have recoil.

    Hope I have answered your question. If you have any questions in the future, you will do best to ask on the most recent day's blog which is found at this address.


    More people will see your question there than on an older blog article.

    Happy shooting,

    Slinging Lead

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