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Education / Training How to mount a scope: Part 5

How to mount a scope: Part 5

by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2
Part 3
Part 4

This report covers:

  • More scope stuff
  • Swap the rings
  • Spiraling pellets
  • What to do about spiraling pellets
  • Misaligned scope
  • How to correct the misaligned scope
  • Setting up a rifle
  • BB did NOT say all bundled scopes are bad!
  • Scope stiction
  • Sighting-in for one distance
  • Summary

More scope stuff

While we are finished with mounting a scope, there is more to tell. A lot of it does come to the forefront when you mount a scope, so it is germane to this discussion. We have touched on some of it before, but today I hope to tell you how to deal with it.

Swap the rings

This is a trick that can help resolve many of the problems we will see today. It’s also one of the big reasons that I prefer 2-piece rings to 1-piece. Someone asked last time what can be done when the scope’s axis is out of alignment with the barrel. Well, that is often the case. The way you find it out is — after you sight the rifle in you try to shoot at different distances and discover that your pellet is off to one side or the other. What can be done?

If you have 1-piece rings you can sometimes remove them and turn them around, so the ring that was in the rear becomes the front ring. I say you can do this only sometimes because you may be scoping a recoiling spring-piston rifle and you need the scope stop pin that’s built into one end of the mount. If that’s true you can always install a separate scope stop, but that pushes the whole scope mount forward and what does that then do to your eye relief?

With 2-piece rings you can make the same swap as the 1-piece, plus you can also turn either ring around — or both! We like to think that our scope rings are perfectly bored and aligned with their bases, and that’s often true, but when it isn’t it makes installing a scope a lot more difficult.

Spiraling pellets

Do pellets spiral as they travel downrange? I have seen them do it as I watched the target through a scope. I had bright sun behind me to reflect off the pellet skirt when this happened.

The pellet is traveling down range in a spiral path. Their movement is not caused by the wind. I ruled that out because of the tightness of the groups and because the wind was under 3 mph on the day they were shot. That leaves spiraling as the most likely culprit –- assuming I am right in my suspicions. For the sake of discussion, let’s say I am right and the pellets are spiraling.

spiraling pellets
This graphic portrays a pellet that spirals as it travels downrange. Even if you don’t see it through the scope you can see the results of it in the groups that are shot.

The only thing I can think of that would cause spiraling is an unstable (yawing) pellet that precesses around its axis in the direction of the spin. If you have ever seen a washing machine become unbalanced on the the spin cycle and hop around the floor in a certain pattern, you have witnessed the phenomenon of precession. Or, watch a top as it runs down.

pellet yaw

It has been known for over a century that bullets can precess. I believe it was discovered very shortly after elongated bullets were first used in rifled barrels. Years ago, I read an article in The American Rifleman about a test on the brush-bucking ability of a .30 cal. bullet. Once stability was disturbed by a stout branch, the bullet began to precess in the direction of twist in an ever-increasing spiral. Of course, that test is not the same thing that I’m discussing here, as the instability there was induced mechanically down range by the bullet striking a broomstick rather than yaw at the muzzle and differential air pressure. But it does show that bullets can travel in a spiral path.

Bullets (and pellets) can also be made unstable by their twist. Varmint shooters are aware that thin-jacketed bullets have been known to explode in flight from the centrifugal force of their spin. And tumbling, or more probably precession coupled with pronounced yawing, is well-known from the early days of the M-16’s development. I remember that a rifleman had little chance of hitting a man-sized target at 300 yards with early M16 rifles. The bullet design/twist rate combination had not been worked out correctly at that time.

With a right-hand twist, the precession spiral would be clockwise from the shooter’s perspective. I would also expect the spiral to enlarge as the pellet gets further from the muzzle.

Okay–so what does all this toffee-nosed drivel mean to real airgunners? It means that even if you correctly adjust your scope for trajectory, there’s still a big chance you won’t hit that half-inch kill-zone at 15 yards. Not because you’re too high or too low, but because you are too left or too right! If you’re throwing a spiral and your pellet isn’t centered on the line of sight at the range you expect it to be, you could miss.

What to do about spiraling pellets

Don’t shoot them! Find other pellets that don’t spiral, because they don’t all do it. If you can adjust the velocity, such as with a PCP, try that. My experience, though, is that if a pellet spirals from a certain airgun it tends to do it all the time, regardless of what you do.

Build a Custom Airgun

Misaligned scope

Sometimes the optical axis of the scope is not aligned with the bore. This will give you similar results to the spiraling pellet, with some important exceptions. The first of these is the fact that the pellet will always be on one side of the centerline until it crosses over the line at some distance. Then it will remain on the other side. A spiraling pellet moves back and forth across the centerline.

misaligned scope
When the scope isn’t in line with the bore, this happens. It may be very subtle and difficult to see and the slant can go either way — to the left like this or to the right.

The second exception that the misaligned scope gives is the pellets fly in a normal trajectory. Pellets that spiral do so up against gravity as they fly downrange. The center of the spiral drops in the usual way but as the spiral widens, these pellets sometimes actually appear to be rising! You have to keep in mind that these pellets are actually flying on their own, due to low air pressure on one side. Thus they seem to defy the laws of physics.

How to correct the misaligned scope

There are a couple of things to consider here. First — is the scope base on the rifle the thing that’s misaligned? Reader shootski talked about having to correct a firearm that was drilled and tapped for scope rings in the wrong place. If that is the problem, you should first consider whether it’s worth the time and effort to correct. If it is, spend the time and money to do it right.

Once the scope base is either fixed or ruled out your next concern are the rings you intend to install. Are they worth it? A $10 pair of rings from the discount store can give you many of the problems we have just discussed. I own many dozens of rings, but I only use the ones I trust.

Once you have the rings you intend using, remember what was said about swapping them end-for-end and even turning them around individually if they are 2-piece. When you have exhausted all the repositioning options, consider using a different set of rings. I know this flies in the face of shooting on the cheap but which would you rather do — save money or hit your target? 

Setting up a rifle

You buy a new air rifle and there is joy in your castle! This new rifle will solve all your problems. It is infinitely accurate (whatever that means) and powerful enough to get the job done. Let’s say you stretched for this one and the new rifle cost you $280, delivered. But wait! You are not done. Figure another $100-150 for a decent scope — not a world-beater but also not one from the bargain barrel. Mounts will cost another $20-50, depending on the rifle and what you want to do. Your $280 investment just swelled to $400 to $480. That’s how much your new air rifle really costs! No wonder so many people swear by open sights!

Then, and only then, do you get to go through all the steps we have addressed in these five reports. Oh, and someone says, “That’s why I always buy the scope that comes bundled with the rifle I’m buying.” And do you also take delivery of that new $45,000 ATV with the tires they put on at the factory? Now, I know that remark is going to start a firestorm of controversy, or at least it should. Unless you guys don’t know tires!

If there is a lot of discussion about the tires, just substitute bundled scopes and scope mounts for tires and you will understand what I am telling you. Are all bundle deals bad?

BB did NOT say all bundled scopes are bad!

No, all scopes and mounts that come bundled with rifles are not bad. Let me give an example. The Sig ASP20 that’s bundled with the Whiskey 3 scope is a great deal! Yes, it does cost a lot of money, but it is a perfect example of you get what you pay for. It’s not a bundle where they are getting rid of scopes they can’t sell.

There are other good bundled scope deals. Look to the dealers who bundle — they seldom have warehouses of scopes to get rid of, and your loyalty means a lot more to them than it does to a manufacturer who looks to three or four major outlet chains as their primary customers.

Scope stiction

This is one you need to experience to appreciate. Some scopes resist being adjusted until they are jarred once or twice. These tend to be the less expensive scopes and they usually wind up on spring-piston rifles that have all the jarring they need. This failure to move to the new adjustment is called stiction. I’m not qualified to explain what it is, but I think it is a combination of static electricity and a weaker erector return spring — or a spring that is fully relaxed.

The solution to stiction is to bump the scope with the heel of your hand after every adjustment. Either do that or fire the rifle twice before firing for record. I wish I could tell you what to watch out for, but all I know is when a scope doesn’t have stiction it becomes one of my favorites!

Sighting-in for one distance

This is not about any special techniques or tricks. It’s just an eye-opener that we all need to be aware of.  When you sight in a scope for one distance, like 100 yards, and you leave it there you solve a large portion of all the scope problems there are. Canting is still an issue but all the stuff I’ve discussed today is moot.

It’s only when you want to use your scope at different distances that these things arise. And there is something you can do about it. Use the lowest power magnification you can get away with. I don’t expect you to shoot squirrels at 100 yards with a 2-power scope, but 6 or 8 power is much better than 32 power. Why? Because it takes your focus off minutia. It does what open sights do, only it also helps those whose eyes aren’t up to the task.

Field target competitors are an exception to this, so they need to set their scopes to work well between 10 and 50 meters. They could care less what happens at 60 meters, where a hunter has to care. The field target competitor has a harder job because of the range in which his scope must work, but at least there are boundaries.


I have addressed several concerns you readers have raised, plus a couple of my own. I will watch the comments to this report to see if any more in this series are required.

author avatar
Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

88 thoughts on “How to mount a scope: Part 5”

  1. From what I have seen causing a pellet to spiral has been from a bad crown at the muzzle end of the barrel or a pellet clipping a baffle in a shroud or such.

    And I had something really cool happen the other day. I had the morning sun on the left of me shooting. And I decided it was time to oil the o-ring on the probe or in the barrel on some of my guns I been shooting.

    I just shot out in the field at no particular target. What happened?

    I got a nice like moisture vapor trail off the pellet. It was the oil doing it for some reason. Or I guess it always does when I oil the barrel. This time I guess I had the right sunshine. It only lasted the time of the flight the pellet was in the air. Probably not even a second long. But I sure did get to see the trajectory of the different guns pellets.

    I could tell real quick what guns were flatter shooters than the others. Was glad it happened.

      • Deck
        Now that’s a heck of a question. Really. Good question.

        First off you now how much I shoot. I shoot a average of 4 hours a day. And I shoot multiple guns. And they are usually always the same ones. The only reason they are different is if I add a new gun to the mix of the others I shoot.

        The thing is I shoot at paper at different distances and I know how my guns shoot. I always make sure I know that for them guns.

        So I’m sure you know the answer already.

        Nope no surprise for me with thier trajectories I saw.

          • Deck
            And remember. I’m not retired yet.

            And that is every week day and weekend.

            And really I probably shoot more than that because weekends are 8 hours for each day.

            Yes it is just as fun as some of my other hobbies. 🙂

            • Gunfun1

              Lots of hobbies are key to retirement happiness plus church. Has been the best 21 of a wonderful 81 years. I have too many hobbies to list. I used to play amateur tournament golf and still play 3 times weekly but shooting targets with airguns is my daily love. Having shot firearms all my life, discovering the airgun world was almost too good to be true. I’m preaching to the choir in your case but this is for readers new to this hobby. Having the satisfaction of point of impact (POI) on a target being almost exactly the same as point of aim (POA) is as rewarding as cranking out a 275 yard drive with a slight draw.


              • Deck
                Well I’m going to take those words wisely. I hope I can make it to 81 years old. And I hope I can still do my hobbies if I get there.

                If anything I’m going to keep on trying.

              • Decksniper,

                Or even better, a par 3 with a 7 iron dropping it in the cup off the flagstick from the tee. Sadly never pulled that one off but a friend did and that was just too slick.


  2. B.B.

    FWIW-Porsche pre-owned cars with a dealer warranty, specify which tires are acceptable.
    I agree the Whiskey 3 scope is quality, however, 90%+ bundled scopes are not.


  3. BB,
    there always seems to be new things to learn on this blog. I for one appreciate the chance to sit at the feet of a master and learn them. Especially since there are so many doing blogs and reviews that don’t seem trustworthy. (trying to be nice) I thought I had a fair handle on how to mount a scope until read this series and realized how much I don’t know. Anyways, I appreciate this series.


      • B.B.,



        Everytime you make a comment like that it makes me think of this:

        “Those of you who think you know everything
        are annoying to those of us who do!

        Still trying to learn at least one new thing every day…most days it is still all too easy to learn far more!


    • CB,
      One of my 27s had an old scope. I had thought I knew everything about scopes playing with that, until I read BB’s blogs. Now, I feel I have to forget my hearsay knowledge on them and restart from scratch.

      • Fish,
        a friend of mine had an older Benjamin Regal NP that he was really struggling with. Being an ‘airgunner’ of some sort to him, he asked, and I agreed to check it out and see if I could make it better. The scope needed ‘centered’ (which I learned is not the correct term in the first of this series) because the adjustment was cranked to high, and it desperately needed different pellets. I used the artillery hold, tightened up the screws, and tried several different pellets, and went from not keeping all the pellets on a 12″ x 18″ box at 25 yards, to about 1-1/4″ at 25 yards. ALL of the information that I used to make that happen I learned from this blog.


  4. Brent,

    Concerning your seeing the Origin in .22 with pump for $224.

    If you buy one with the pump for $224, I will be more than happy to take it off of your hands.

    As far as your Maximus is concerned, look for a Discovery stock. They are the same. I have seen some nice custom stocks for the Discovery. Or you can sell it to me. 😉

  5. BB,

    Lots of good info here. The one thing I would add would be that if nothing is working on fully correcting the misalignment of the scope, a pair of adjustable rings with adjustable windage might be the next step. However they do tend to be pricey, and I only use them on PCPs – I don’t know how long they would really hold up on a strong recoiling springer. But they do let you get the barrel and scope axis lined up on guns that are pretty far out of alignment.


    • Alan,

      I’ve never used adjustable windage mounts.

      Guess that you would sight in at a range (say 30 yards) then shoot test groups at minus 10 yards and plus 10 yards, tweaking the base to eliminate the error as you go.

      How do you go about setting them up and aligning the two axis? Do you have a special way of doing this?


      • Hank,

        I like to first optically center the scope with the V-Block approach BB talked about earlier in the series, and set up the rings so they are in the mid point of their range for both vertical and horizontal swing. Then I mount the scope using the mirror method I mentioned in the comments in the prior blog in this series, and see how things work out on paper at close and 20 yards. I do try to get the lateral POI where I want it by moving the front mount if needed, and skew the vertical as BB suggests to get more usable scope range for longer shots, fine tuning the zero with the scope turrets. If I can’t get outside for longer range testing, I will finish it up with clicks on the turrets, but I don’t adjust my re-settable scope knobs until after the I get to test things outside in the next step.

        I like to go out and see how the lateral movement shifts at longer ranges, which is usually the 55 yards to my backstop in my backyard. If I see more than a few clicks of lateral movement, I then back the scope up to the lateral value that was the optically centered value and shoot a few shots. I then readjust the windage via the front scope mount only – this will set me up to have everything inside this distance off by no more than any small remaining offset from the scope optical axis to the bore axis, which probably is not much more than at most a quarter inch or so. So far I have never found it beneficial to mess with the rear lateral mount – I just use it as an anchor point (although it has to be loosened when moving the front to allow for a stress free pivot point, as the system is designed to work).

        And I always reconfirm that the scope reticle is centered on the muzzle with the mirror test – worst case I would reset it and do it all over again if it was off by much, but I have not had one off that much yet.

        Hope that helps.


        • Thanks for the detailed reply Alan! Appreciate that!

          I will (quickly) check and adjust a scope with mirror (with a piece of 1/4 plate glass on it) and a flashlight to get it “close” then I will use the V-block approach to finish up the initial centering.

          When setting up a “hold-over” rifle I will mount the scope, check POI at close range (12 feet or so) and shim if required before sighting in at the near-zero then confirming POA & POI at my far-zero. With my point-blank range (typically) being 20 to 40 yards that drops my far-zero at around 34 yards and that leaves me setup pretty good out to my maximum effective range (max one inch groups) of 50-55 yards for small for plinking and game hunting. Never looked at windage adjustment on mounts.

          Will be looking at this closer when I start shooting at longer ranges. Currently I am testing and trying various tunes (15; 18; & 25 g pellets in two different barrels) so it will be a while before I start going for longer range. Then there are slugs to consider – will be busy for a while 🙂


      • Hey Hank,

        AlanMcd has added to our posted wealth of knowledge with his reply to you. I’ll add that much of what he does is exactly what i do. If you are forced to do this outside be certain you have NO wind and that means a number of good wind flags and Telltale are absolutely required in my opinion. Most folks can’t feel a 2 mph wind on their face and fewer can tell what direction it is from; but my opinion only.

        I will add to your reading since the snows are already blowing or soon will be :^)


        I find it always helps to get good information stated multiple ways. I think this is one of the better if not best sources from a retailer…beside B.B. of PA! Look around they have a wealth of information around their site.



        • Shootski,

          Excellent point about making sure there is no wind. I always do that when going out to confirm/finish a scope set up – I look at the foretasted winds in advance and plan for days that will be good, and I always do it in the morning when winds are the quietest. Fortunately my backyard range is behind the house and down a hill, so when there are very light winds I get almost no movement back there.

          The best days for such shooting are days when I am running the smoker with a brisket on it – having that smoke linger in the air sure shows the movement, or lack thereof!


  6. B.B.,
    There was a lot of useful info in this scope mounting series, thank you! It takes a lot of patience to sort out a scope mounting properly! I never considered that there was more than using rings of the right height, attaching the scope and adjusting it to hit the bull. The simple drawing with the two lines made it easy to understand the effect of left-right scope misalignment when shooting before and beyond the sight-in distance! That thought never entered my mind before! Wow! If useful information was food, this blog would be a five-star restaurant!

  7. Some scope mounts, like certain Leupold and old Redfield bases/rings can be adjusted for windage. This can be a big help if the receiver and barrel are out of alinement. One other comment, the original M-16 used a 55 grain bullet with a rifling twist of 1″ in 14″. That was OK in mild weather but bullets would keyhole in freezing temps. A change to a twist of 1″ in 12″ fixed the problem.


    • Depends on what magnification you use and if you have a true mildot scope.

      Pretty simple stuff. That’s already been talked about a long time back on the blog.

      But would be a good subject for someone new getting into range finding with a scope.

      Maybe that should be on the next series of reports of how to use a scope.

      Here is one of the blogs.

      Try Chairgun. Its a balistics calculator for Hawke scopes from Hawke scope. But it works with other scopes too.

    • Fish,

      I always use the military WORM formula. Divide the width of the target in meters by the mil measurement in the reticle and multiply by 1000. The thing is — you must know the width of something in the vicinity of where you wish to range and your scope or binoculars must have mill dots and not MOA dots.

      I was a tanker and we knew the approximate size of enemy tanks width, length and height in meters, so this was something we could do easily. How a civilian might do it is a different matter.


      • BB
        Fish was talking height so that would be good for what he’s talking about too.

        It doesn’t have to be width.

        I’m betting the only reason you used width because it gave the biggest profile of the targets you shot at.

        I totally use a height dimension if I range find birds. And I still use height if its a rabbit and such.

        If you vertical range find you have balistics. If you horizontal range find you have windage.

        I range find off of vertical then do my hold offs on windage.

        That’s how I have always done it.

          • Fish
            I have been flying since I was about 9 years old. Started out on gliders then progressed to regular planes.

            I have even flown helicopters fuel and electric.

            Now I fly electric. The motors and batteries have came along way from back like they use to be.

            Right now I fly outside 3D flying. It’s a 40 inch wing span flat epp foam profile plane and it uses carbon fiber rods for re-enforcement. The plane weighs about 2 pounds and has about 4-5 power to weight ratio. So I can hover the plane out in front of me with the nose pointed vertical then punch the throttle and it will take right off vertical. Plus the plane will fly very slow in normal level flight. It will even fly on the stall with no tip stall. I have added extra stall tabs on the leading edge of the wing. It’s a very stable plane to fly.

            Oh and I just got a few months back a pusher prop YF22 where the motor is in the middle of the fuselage. Another fun plane to fly.

            I read you and Shootski’s comments when you was talking about planes. It sounds like you like flying.

            • GF1,
              Wow, you’re a serious RC pilot, the real deal. Cool! Man, you’re an expert on airguns and RC aircrafts…
              I had done paragliding for a short time. I had a blast but saw a couple of sad accidents too – like bull riding, not the smartest idea. I played with RC planes awhile years ago. Slow stick, Slo-V kinda things – pretty much flying toys. I also played with indoors micro RC planes. Before I quit the hobby, my biggest achievement had been building a flying wing slope glider from foam. No motor. No rudder. Only elevons. On a windy afternoon, it would fly forever over a hill, catch thermals and such…
              Talk about new batteries. Take a look at this ultralight. The pilot pretty much sits on a big pile of lipo. And the battery cover is very thin to keep the plane light. I say only the unreasonably brave pilots must be flying it. 🙂

              • Fish
                By far no expert. Just trying to have fun and learn.

                And para gliding is cool. I think I would rather do that then hang gliding. And the accidents is probably what keeps me away.

                And you should start flying rc again. It sounds like you was doing pretty good.

                And cool link. A battery powered plane you can fly in. Amazing what’s out there now days.

                In a minute I’ll post a few pictures of some of my planes. I’m at work right now so I can’t do it till later when I take a break.

                • Gunfun1,

                  Wow! Gunfun1 that is a fantastic looking BIRD!

                  The Walter Extra airplanes are some super acrobatic machines. I didn’t know they had a RC version. I got to fly a two seater with a German pilot while i was stationed in Stuttgart in the 80’s. One of the things i taught as an instructor was aerobatics/formation flying. He wanted to learn a few aerobatic routines that had bedeviled him for months. I nearly killed him doing an outside loop; something he had never done.

                  I may need to look into that in RC it has got to be fantastic if it flys anything like the full size one does! Although the T-28 was still rated at +12, -6 G when i flew them they had to de-rate them later on to +6 and -3 G because of airframe fatigue. I had nothing to do with any of that airframes fatigue ;^)

                  I think whatever I fly in RC is going to require some serious reinforcement so i don’t turn it into a momentary formation flight of parts!


                  • Shootski
                    Yep definitely reinforce that bird when you build it.

                    The RC versions when flown all out a pilot flying the full scale version would never be able to do it.

                    You can make the rc planes violent with the control surfaces. You have to tame the throws or have good stick control to fly a RC plane scale like. Or a computer radio. Which everybody has now days. Back when I started flying it was all stick flying . No computer aid. I didn’t have my first computer transmitter till probably 9 or 10 years ago. The computer helps no doubt. But you still got to know what your doing.

                    And what your going to find is that the RC planes have the same flight characteristics as the full scale plane.

                    I’m tell’n ya your go’n to love RC planes once you get into it.

                    And remember. You might crash a little when your learning. But you will really start crashing when you think you know what your doing when you start pushing the limits. How do I know that. 😉

                  • Fish
                    Now you know those pictures are probably about 25 years old. So I don’t look like that anymore. Probably about 35 pounds heavier and alot less hair.

                    Well the top 3 pictures anyway are 25 years old. The YF22 is recent. And it’s about a 30 inch wingspan.

                    But build that glider. I know you will be happy all the way around.

                    I can say this. I have probably had the most fun in my life hobby wise flying RC planes.

                    Go for it.

                    • gf1,
                      but then there are these guys…
                      well, i’ve enjoyed several hobbies, but my heart belongs to the ocean at the end of the day. sailing is my calling, true passion. when i saw the mediterranean sea the first time, i was a little kid and instantly fell in love. since then, there has been only one genuine motivation in my life.

                  • Fish
                    I forgot to say that the A10 and 300 I built from a kit that a person made up. They was not store bought kits. So both were kind of rare. They was balsa and light ply construction and I covered them with Monokote. So the design pattern on the 300 I cut out myself. The decals for the 300 I found at a place that dealt with scale RC planes. Can’t even remember the company name now.

                    But what is funny now days is most everything is ARF’s (almost ready to fly). I use to enjoy building the planes too back then as well as flying them.

                  • Fish
                    Yep the Mirage are cool. I pretty much like all planes.

                    I haven’t really never got into sailing. I like it but never done it. I did have a john boat that we paddled around the lake fishing which is now a state park. So its a pretty big lake. But that’s been about it for me as far as water goes. But that is one of my other hobbies. I like bluegill and crappy fishing.

                    So much to do in the world if you set back and think about it.

      • BB,
        Tanks are difficult; you are moving, the target is moving, and the list goes on…
        Width calculation will work if you know the angle you are looking at the target.
        I think using a scope on an airgun is more complicated than using it on a firearm; most issues probably occur in shorter distances. If you’re shooting something at over 100 – 150 meters, for example, do you necessarily need parallax compensation?
        Anyhow… So were you a tank commander? That’s impressive.
        PS: I think you should get rid of your 23 to make room for your new 27. 😉

  8. BB
    In your example of a rifle shooting to the left of Target at a father distance and to the right of Target at a near distance. The question is which direction do I need to move my scope to correct that condition? Am I thinking correctly that my scope is pointed off to the right of the bore of my rifle?
    I have exactly that problem with one of my rifles.

    • Pete,

      Move the front of the scope in the same direction that you want the pellet to move. In other words to correct a rifle that shoots to the left, move the front of the scope slightly to the left (and the rear will move to the right). If you have a hard time visualizing what I’m saying, get two straightedges and put one on top of the other. The bottom straightedge is your barrel and the top is your scope. Point the bottom straightedge to the left of the top one. Keeping them at the same angle to each other, when the top one moves to the left and what happens to the bottom straightedge? It comes in closer to the top straightedge, and will be closer when the “gun” fires.


  9. Really enjoying this series B.B.!

    Good to have all these details in one place to refer to (I’ve sent links to a couple of people).

    With reference to pellet spiraling, in addition to GF1’s comments of mechanical issues I believe that two other things that might contribute to this problem…

    One is mechanical – pellets loaded with their axis misaligned (canted) to the bore due to pellet probe or magazine issues.

    And the second being air turbulence. Think that too much air jostling the pellet as it leaves the bore can cause problems with pellet stability. Seen this playing with different tunes on my Impact. Too much power (reg pressure, hammer spring and valve dwell) for a given pellet and barrel length results in a large (loud) muzzle blast and poor pellet flight. Tuning the volume of the air pulse such that little or no air is wasted (after the pellet has left the barrel) improves efficiency, quiets the gun and gives better pellet flight. I’ve seen small changes in tune make a big difference in group size – which might explain why one pellet might shoot better than another. …Just my observations.

    Oh, per your comment “It is infinitely accurate (whatever that means) and powerful enough to get the job done.” IMHO that means a FWB 300 – it’s just awesome within its effective range! 🙂


    • Hank
      I have had to much air still in the barrel causing accuracy problems. Its like it pushes the pellet as it leaves the barrel.

      My Hatsan pump pcp was like that. I slowed it up about a 100 fps and it is so accurate now.

      And the thing I found about pellets canted or loaded wrong is the pellet outside diameter at the head or skirt gets sheared off or disformed of some sort.

      Definitely alot of things to do right when you shoot. More than can be imagined until you start shooting and keeping notes.

      As we have said before. The deeper you dig the more you find.

      • Gunfun1,

        That extra air/gas in the barrel spilling out right as the projectile base exits the muzzle is why the silencers typically increase the shot to shot accuracy of PB as well as airguns. I have a 10.5″ Donny FL Emperor v3 on my .308 and it is more accurate over a bare muzzle. It gets even more accurate with the 6.25″ expansion chamber added; not to mention it does a good job of bring down the report.


        • Shootski
          Yep I have had my Marauders shoot more accurately with the shroud and baffles on the gun. Tried them with the shroud and baffles off the barrel and got worse accuracy.

          Not to say that is true with all guns though.

  10. One of the great things about being newly retired is I can Indulge myself in one of my favorite things to do, looking for air guns in pawn shops more often. On Monday, I found an IZH 48 in one of my favorite haunts. It had a soft bag extra seals and seem to be in pretty good shape and was at a good price. I would prefer that you don’t buy it just because you have deep pockets. Please leave it for someone who’s always wanted one of these but didn’t think they could afford it. I would appreciate it. Here is the info:

    Tolliver’s Pawn and Gun
    Manchester, Tennessee
    (931) 728-2360


  11. Everyone,

    Here is a Winchester 427 (Diana 278) on eBay for Buy it Now.


    It’s $255 and $35 shipping so you’ll pay $290 to get the gun. It looks complete and in good condition. It’s all the money and a little extra for a Diana 27.

    The thing is — I don’t wanna hear any whining and crying over this in a week. If you want one, it could be yours!


    • BB
      I thought you was going to say you didn’t want to hear any whining if it didn’t turn out to be a good gun.

      How do you really know? Especially if you don’t know the seller.

  12. B.B.,

    This has been a great series. Demystifying mounting a scope and trouble shooting problems afterwards.

    Pellet spiraling is a very common problem. Many have already stated potential causes to help diagnose solutions. To these I will add CLEAN YOUR BORE. This especially applies to powerful pcp’s that begin to spiral pellets.

    I have a request that seems to belong in this series and I’ve never read anything from you about the subject….

    Creating a range card or marking your wheel on your scopes parallax. Since you shot FT I’m sure you’ve seen a variety of options for either clicking or holdover that is simplified in a range card or wheel markings or markings on an enlarged elevation turret.

    • Kevin
      I use to do that.

      For the longest time now I reduced my shooting magnification down to 4 power. I use to shoot at 10 magnification. I would range find and mark the tape on my big side wheel.

      Now I’m focused at 15 yards and up at 4 magnification. Now I have my mildot holds and everything in between the dots logged on a cheat sheet if you will for different distances.

      Like say 25 yards is 1-1/2 mildots under or 65 yards is 1-3/4 mildots over.

      How I came about that is I shot at different distances and logged what hold I needed. Maybe a little more work but I know where my guns are going to hit when I aim.

      There are 3 of my airguns that are used for pesting. My modded FWB 300s, the TX200 and the .25 Condor SS. Notice how the power goes up in each gun. But those guns I know my holds on. The others I just plink with at my targets and spinners. But I still know my holds.

      But thats how I do it.

        • Kevin
          I have tried clicks but stiction always gets me.

          When I use holds my scopes are zeroed and it’s up to me to do my hold offs right. That way I don’t have to worry about the mechanical variables.

          I know. Alot of people use clicks. And it works. But I’m all about eliminating variables. Well as much as I can.

          And yes I know the quality of the scope matters too. I have had 5 and 600 dollar scopes. But no $2000 scopes. And probably will never own any that cost that much.

          So for what I do and shoot at works for me.

          No argument just saying what I have seen and what I need to happen.

            • Kevin
              Now that’s another good thing.

              Mark you holds also on the wheel tape for hold along with the distance.

              That would be a deadly combination if all the other variables fell into place.

              • You only need to mark your holds/mildots on the tape since once you’ve dialed out parallax you can read what your holdover/holdunder should be. You don’t care about distance since the tape tells you where to hold for poi.

                Not sure what you mean by “all the other variables” since you still need to zero your scope at your preferred distance (I like the apex), then shoot at various distances and mark your sidewheel. With the ranchero set on high it’s dead on at around 17 yards and again around 30 yards. With a clean tape overlaying yardages on the large parallax wheel these two points (17 & 30 yards) get marked with a + (put the crosshairs dead on). For other distances it’s +1/2 (hold a half mil dot high), -1/2 (hold a half a mil dot low) and so forth.

                Other than weather temperature, there aren’t any other variables.

                • Kevin’s
                  I mean your hold the pellet and wind and such for variables.

                  And yes I know what you mean that you have your focus already figured out for the different distances and then you added the holds on the tape at that distance.

                  That way it’s all right there instead of looking at your cheat sheet on your flip open scope cover or where ever you keep it.

                  I was just saying it’s a good idea that the holds are noted at your focus distances.

          • GF1,

            Know what you mean about stiction.

            Seems that (most?) scopes are not designed to be dialed for every shot. I have had (modestly priced) scopes that did track well but most did better if I over-shot the the mark and stepped back (rather than trying to adjust one-click) to take out any lash.

            It never bothered me because all my shooting was at less than 50 yards and hold-over was that name of that game.

            Recently, with my FX Impact and shooting at longer ranges, dialing has become more important to me. You might want to check out the Elements Helix scope ( 6-24×50 ) which is designed for dialing. Its reasonably priced and (after a month of use) I am quite pleased and impressed with it.


            • Hank
              I’ll check out the scope. But I still use good ole fashioned Kentucky windage for even my long distance shooting. That being hold overs and such.

              It’s just what I’m use to. So that’s how I do it.

    • Brent
      Yes they are. I got a target that has 9 circles on it. I shot each of my guns at a circle. Some are 10 shot groups and some are 20 shot groups.

      They are all at 50 yards. And I marked what gun and how many shots in the group.

      I’ll try to remember to post a picture tomorrow. But Crosman isn’t the only one making good barrels.

    • Brent
      Here’s the picture. Oh And I forgot to say. Notice the 54 Air King groups. I switched to a new tin of pellets and it doesn’t like this tin for some reason at all. It was grouping like the other guns with the last tin I just finished up. It really liked the first tin of the Hades pellets. But not this tin. And also all the other guns shot are with the JSB 10.34 pellets if anyone is wondering. And the other guns did not like either of the tins of the Hades pellets. They shot ok but not like the JSB10.34’s.

  13. “toffee-nosed drivel” that’s a new one on me. Also if these pellets spiral… don’t use them.. Doctor it hurts when I lift my arm. Well then don’t lift your arm.

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