Scope dope — I hope! Part 4

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

Part 1
Part 2
Part 3

This is an ongoing series about scope questions and issues. Blog reader David Enoch asked for it originally, but many other readers have jumped in since it began. Today, I’ll talk about adjustable scope mounts.

First things first
Why do we need adjustable scope mounts? Aren’t the scopes, themselves, supposed to adjust? Yes, they are, but 2 things quickly become a problem. First, the scopes don’t adjust as far as we need them to; and second, when a scope adjusts toward its upper and right limits, it loses its precision. I will address the second problem because it’s really the principal one.

When we look at a scope, we see that it has a range of adjustability and assume that it’ll work as it should throughout this range. But that’s not the case. Inside each modern scope there is a smaller tube called the erector tube. The erector tube often contains the reticle; and as the tube moves up, down, left and right, so does the reticle. So, moving the erector tube is what moves the reticle.

There is a spring or springs that press against the erector tube, making it press against the adjustment knobs, in turn. That spring has a range of movement it goes through as the tube moves. When the tube is up high or far to the right, then a spring or springs that press it against the adjustment knob or knobs are relaxed and can allow the erector tube to move when the gun vibrates, such as with a shot. This is one of the chief causes for “scope shift.” You fire the gun, and the erector tube moves slightly, taking the reticle along with it, of course. On the next shot, the scope will be aiming at a slightly different place. It’ll appear that your scope is wildly throwing the shots around.

scope knob adjustment range
This elevation knob is adjusted up to its maximum limit. I recommend not adjusting it higher than the number 3 line on a scope like this to avoid scope shift.

I tell folks that a good rule of thumb is to not adjust their scopes above the 3/4 mark on the elevation knob or past the 3/4 mark on the right windage adjustment. Some scopes can adjust farther than this without a problem; but the closer you stay toward the middle of the range, the better. If your scope doesn’t have knobs like these, you may have to count the actual clicks of adjustment to know where you are.

Is adjusting the scope in the opposite direction (i.e., down or to the left) a problem? No, it isn’t. You can adjust all the way until the adjustments run out in the down and left directions. It doesn’t hurt the scope, nor does it affect accuracy.

So, the scope that you thought had a huge adjustment range turns out not to have as much as you believed. Yet, your airgun (or firearm) needs more adjustment than you have. How do you compensate for the adjustment you no longer have but may need? With a scope mount that adjusts, of course.

Adjustable scope mounts
The purpose of an adjustable scope mount is to align the axis of the scope in a direction different than the scope base on the gun dictates. If all scope bases were aligned with the axis of the barrel, there wouldn’t be a problem, but they aren’t. Adjustable scope mounts can compensate for this, leaving the scope’s internal adjustments to serve the ballistic requirements of the gun in question.

Up and down, left and right
A barrel can point off from a gun’s scope base in any direction, but the most common direction is down. The barrel “looks” down, in relation to where the scope tries to look. The other 3 directions are also possible, with left being the second most common. After that, the other 2 directions happen pretty infrequently.

So, if you’re going to need extra adjustments, it will most likely be extra “up” that you need, followed by extra “right.” Adjustable scope mounts have to provide extra scope movement in all directions, with up and right being needed most often.

Scope tube integrity
The scope tube is a hollow, rigid tube that must maintain its integrity to keep the lenses in alignment. If the tube were to bend, it could seriously damage or even break the scope. Adjustable scope mounts must either move the scope as a whole without putting any stress on the tube, something that only a 1-piece mount can do; or they must adjust in such a way that when the rear mount moves, the front mount can relieve the stress on the scope tube. Only the B-Square AA adjustable scope mounts were able to do that; and when B-Square sold the company several years ago, the new owner moved the manufacture of the AA adjustable mount to China, where the quality control was soon lost. You cannot buy new AA adjustable scope mounts any more.

Benjamin Marauder old style magazine
When the rear mount is raised above the front mount, if the front mount doesn’t move to compensate, the scope tube will be strained. These B-Square 2-piece AA adjustable mounts have rings that pivot forward to allow the scope tube to remain straight.

Sports Match has 2-piece adjustable mounts on the market; but as far as I can see, they make no provisions for relieving the stress on the scope tube when the rings are adjusted separately for elevation. I guess I need to test them to learn their operational parameters. I don’t see how they can avoid stressing the scope tube when the front and rear mount are at different heights, but I’m willing to hold my opinion until I’ve examined them.

I’ve tested several 1-piece adjustable scope mounts and found all of them to work well in this regard. Most recently, I tested the BKL adjustable mount and found that it moved well in both directions.

What about precision?
To date, no one has made an adjustable scope mount that adjusts with precision for a modern scope. Such mounts do exist for vintage scopes that have no erector tubes because the entire scope has to be moved by the mount. I have shown you this kind of adjustable scope mount a couple times.

adjustable scope rings
This Unertl scope ring adjusts to move the entire scope. It has the same precision as the adjustments on a modern scope.

Slippage is common with adjustable scope mounts
The most common problem is the adjustable scope mount that does not hold its position. That’s why the Chinese-made B-Square adjustable mounts failed. Their screw holes had sloppy threads that tore out under stress, and the mounts couldn’t hold in position. So, whatever adjustable mount you get, it must hold its position once it’s been adjusted, or it won’t work.

And slippage happens soonest on spring guns because of their recoil and vibration. Ironically, spring guns are the very ones that need the adjustable mounts most often. There’s nothing that can be done about this, but you must understand that you don’t want a scope mount that can’t hold its position.

Firearms shooters need adjustable scope mounts more today than ever before. I think that’s because modern guns are being assembled faster and with less precision than they were in the past. The thing is that firearms shooters are not as aware of scope problems as airgunners, so they tend to have more of them; and when they do, the problems are harder for them to resolve. I’ve tried to help people who I knew were having some common problems such as adjusting too high in the scope’s range, but they just looked at me like I was crazy. Surely, no scope manufacturer would field a scope whose adjustments were not 100 percent useable?

That’s all I have for you today. How about telling me your other unresolved scope issues?

70 Responses to “Scope dope — I hope! Part 4”

  • hankmcrae Says:

    Tom and friends,
    Thankfully I have very few scope problems because I listen to my uncle B.B.! I’ve been using an adjustable bkl mount on a 12lb tx/Bushnell elite, all of the above recommended by you. Now, if only I had more time to compete…next year I keep telling myself, next year.
    -hank

  • Gunfun1 Says:

    I just thought of something after I read the above about adjusting to far up and to the right. How it relaxes the erector spring.

    I know we talked before about how a gun will shoot low and to the left in certain instances.

    I wonder why the scope manufacturers don’t put the erector spring in the opposite position of were they locate it now. Down and to the left. That way if you had to adjust up and to the right it would keep spring tension then.

    I know the gun shooting low and left can be from multiple reasons. But shooting low is probably the bigger problem.
    Maybe switching the spring location would help out some kind of way? Does that make sense? Or maybe I’m thinking wrong.

    • RidgeRunner Says:

      You would likely need some pretty high mounts to accomplish such as your knobs would be on the left and on the bottom. You could just twist your scope around in the mounts and have just that. You would also still have the same issue, but in a different direction.

    • GF1,

      The low and left thing is well-known to advanced airgunners and hardly known at all to anyone shooting firearms. So 500-1000 people know about the problem.

      Scope manufacturers aren’t aware of the problem yet. If they were, Leapers would be working to solve it.

      B.B.

  • RidgeRunner Says:

    I fortunately do not have this particular issue at this time, but I do have a scope issue that I am sure is common. Can you adjust a hundred yard parallax scope so you can see through it at 25 yards? All my life I have been using AO scopes and have almost no experience with fixed parallax. I picked up a Ruger Airhawk recently and I cannot get a clear image at less than 50 yards. Is it me or are the air gun companies really such idjits for putting such scopes on air rifles?

    • Slinging Lead Says:

      RidgeRunner

      I have never done it myself, but apparently some fixed parallax scopes can be adjusted. From what I have read you must first unscrew the front trim ring on the objective bell of the scope (if there is a front trim ring.) This will reveal the front objective lens which is housed in a ring of its own. On some (all?) scopes this ring is threaded on the outside edge. This allows the lens to be screwed in or out to adjust the focal length and hence, the parallax. The ring that houses the front lens may have a groove on either side of the lens. These grooves are used like the slot in a flat head screw to give you something to bear against to screw the lens inward or outward.

      I am reluctant to try this procedure myself because I am worried the nitrogen gas or whatever might be released during adjustment and render the scope prone to condensation and fogging of the lenses.

    • Mel Says:

      Don’t be afraid to reparallax your scope. It is a lot easier than you think. Just remove the Objective locking ring and adjust your frontal lens as you would do with an AO scope.

      • Mel,

        My friend, Mac, was going to write a guest blog on this for me, but he never got to it. Would you be up to it?

        B.B.

      • Mark Says:

        Indeed, we have helped several folk using the “pre packaged” fixed AO scopes who shoot 50 yards and less by doing this. For some reason they seem to ship with the focus some where out there at 100 yards or more on a backyard rifle.

        On many AO scopes, the yardage on the bell does not match the actual focal point, I have changed that as well on occasion to match more closely using the same method.

        • BG_Farmer Says:

          The numbers on the bell are probably meaningless :) ! I’ve seen people “range-find” with an uncalibrated scope as marked and it can be off by 10′s of yards/meters. Also, most people think that if it is “focused” that parallax is eliminated. That is only true if the scope has been adjusted for the user, including the ocular adjustment. The A-team procedure is the best and/or you can check parallax on target by head bobbing. I’m sure you know all that, just wanted to make it clear for everybody.

        • BG_Farmer Says:

          PS. The reason I say this is that I have had more than one new AO scope that focused perfectly, yet revealed parallax error on target when bobbing my head. Correcting that can shrink groups 50% sometimes.

    • RR,

      Mac used to adjust the parallax of his scopes all the time. I was going to ask him to write a guest blog about it.

      I don’t worry about it because it’s never been a problem for me. I used to use 100-yard scopes on air rifles all the time, because in the 1970s they were all you could get. Of course I wasn’t using scopes with high magnification, so I never saw how blurry they were.

      B.B.

      • Gunfun1 Says:

        That is what I always use to do on my older fix parallax scopes also.

        I would just turn the magnification down the closer in I shot.

  • zimbabwaeed Says:

    I use Burris signature rings with offset plastic inserts. I center the reticle and then use the inserts to get the group as close to the center of the target as possible. Then I use the scope adjustments to finish zeroing the scope. What are your thoughts re this method of scope adjustment? Ed

  • Fred DPRoNJ Says:

    Or with a worse case scenario, you can always bend the barrel as BB showed us how to do in this blog.

    http://www.pyramydair.com/blog/2012/09/bending-airgun-barrels-part-5/

    The question that just occurred to me is if anyone has done this to a firearm?

    Fred DPRoNJ

  • cowboystar dad Says:

    Well, thanks to this blog (primarily) we have few scope issues anymore.
    We have 6 scopes in total on a mix of airguns and rimfires and can depend on all of them to sit for a month and then put the first round pretty much where we want it.
    This past weekend I started teaching the boys (now 10 &12) how to use the mildots on their Leapers Tactical scopes. We wanted to try some subsonic rounds to see if they improved the accuracy of their Marlins.
    At 100m they’re shooting 1.5-2″ groups…pretty good in my mind for pre-teens (better than more than a few adults at our range, I’m proud to say) with Fed Eagle HV.
    So we figured the drop for the subsonics, translated it to mils and figured out how many dots to hold over. Within a couple of shots they were both hitting the bull…sort of.
    So here’s a question. There was a 10mph wind with gusts to 30. The Fed Eagles were doing what they do, about 2″ in the wind. But the best with the subsonics (Remington) was in the neighborhood of 4″.
    Does the wind play havoc with subsonics…or do their Marlins just hate this round?
    Otherwise our only scope issue is a Leapers 6.4″ Red Dot (their best). It’s adjustments are backwards!!!
    If your rounds are hitting high and want to lower your impact…you have to dial in ‘UP’. Same for windage.
    I can only surmise that’s the way it’s supposed to be…it doesn’t seem like it could be a fault to put the turrets in backwards or whatever.
    But it works fine…as long as you remember to turn opposite of what you expect.

    • BG_Farmer Says:

      I was able to get slightly under 2″@100 yards with Rem. SS’s a few times, but they do fall prey to the wind. 4″ is not ridiculous in non-calm or really steady wind conditions (esp. with 30mph gusts), if I correctly remember the last time I did it under similar conditions. I also have had pretty good luck at 100 with HV’s (usually CCI Mini-mags or Federal AM22) — they may not be as accurate (as measured at 50 yards), but they cut down exposure time to wind and thus deflection. My policy for 100 yards with .22LR is only on perfect days :) ! 100 yards with .22LR is like 250 or more with c/f, for me at least.

      • cowboystar dad Says:

        In other words it’s looking like subsonics are not going to be our cartridge of choice on the prairies ;-)
        We’ve actually had pretty good success with the Fed Eagle…but it’s a rare day in Alberta that there isn’t some wind.

        • BG_Farmer Says:

          Yes, we always have a nice stiff, gusting wind here too, at least on the days I have time to shoot (mostly in the winter). If you can get them, have you tried Federal Automatch 22 (AM22)? Some lots I’ve had are very impressive (.33″ for 5 shots was pretty regular with a couple of boxes) at 50 yards in my Savage MkII), and they are always at least decent, much more like boxed rounds than bulk, although they come in 325 rnd. bulk pack. A little hotter than STD vel. (to work the bolt on autoloaders), but not too hot, and the bullets are not copper washed.

          • Robert from Arcade Says:

            The thing with sub-sonic .22 RF ammo is that much of it really runs at the same velocity as standard velocity ammo, assuming that we are talking about 37(HP)- 40 gr bullets. Also , enviromental factors such as air temperature and humidity, will affect the velocity as well, depending on the range the target is at. So will the length of barrel it is fired in. A lot of HV .22 RF will be sub-sonic at only 50 yards. The most limiting factor in .22 RF ammo is the bullet . If it has a damaged base,( which you of course cannot see ), you will have un-explained fliers. There is a reason why match ammo costs more and it is in the quality control. That being said, some lots of inexpensive .22 RF are quite good in some guns. Also bullets can be damaged by the magazine , and feeding systems in some guns. It is VERY difficult to shoot consistant 10 shot , 100 yard groups with the .22RF . At least I think it is. Most are content with 20 yard hits on small game , and that is ok . Two to 1.5 inch ,10 shot groups from your son’s Marlins at 100 m is very good, and shows that you are on the right track with them.

            • BG_Farmer Says:

              Robert,
              I agree — HV probably slows to subsonic by 50 yards in many cases. I do however think the Rem. SS HP is really slow by 100 yards. I had to collect my meager mental notes, but I recall it was much lower than other ammo at that range, requiring a lot of scope clicks and/or holdover, which means it may slow down even more, being both a little lighter and possibly less aerodynamic (relatively) than solids?

              Anyway, as you say, 100 yards with a .22LR is a trick or treat type proposition, and conditions need to be pretty darn good for even match ammo to perform the way most people want (to talk about); I think 2″ is pretty credible, and 1.5″ quite good, if there is any wind or other contrary condition. Getting 1″ group at 100 yards is more than impressive for me (even 5 shots) with .22LR under any conditions, although I’m not happy with that for a c/f really, if I’m just shooting to shoot a group. Some people say it is easy, though…

              Early morning and late evening are usually the best times, with still air and diffuse light, probably even on the prairie. Those are the times I would recommend trying to extract best groups with best ammo. Other times, I’d stick to the commodity stuff and treat it as an opportunity to learn the wind…once you have an idea of what a particular ammo can do, you can still do technical work with it, relative to its particular limitations.

  • Kevin Wilmeth Says:

    B.B., thanks again for this series. I do learn a lot from stuff like this. (FYI, all of my scope experience thus far has been with firearms.)

    In re the phenomenon of the erector tube “settling” against the spring after an adjustment, I was taught to lightly tap the turret a couple of times with a small pocket tool (usually something like a Leatherman Micra) to precipitate this settling before firing a subsequent shot. (In my case, the scopes in question have nearly always been the low-turret design with screw-on covers and coin-friendly adjustment slots.) I’ve done that for some years now and certainly haven’t noticed any problem–either with errant “settling” shots or with turret marring–but especially as I learn more, the brain sometimes asks for an updated data point.

    Do you have an opinion on this practice? The idea has always struck me with a familiar blend of conflicting ideas: on one hand it seems rather hokey for an otherwise precision instrument, but on the other, if I’m understanding the functional design of the erector tube properly, it also makes a certain sense.

    • Kevin W.,

      Welcome to the blog!

      Yes, I also tap the scope to settle it — when I remember to do so. I should have mentioned that in the report, because it does work.

      Those scopes with the low knobs make it difficult to know where you are in the adjustment range. I have many of them myself, and most are my good vintage steel scopes that I love. But I like the target turrets (the one shown in the photo) for their visibility of the adjustment range.

      B.B.

  • Jim in KS Says:

    I’m still throughly enjoying the blog installments on this topic. Your comment about the limited impact that a small number of airgunners have on large scope and mount manufacturers really hits home. That makes me kind of wonder why airgun manufacturers, themselves, don’t pick up the gauntlet. This issue, after all, affects them and their customers directly. The fact that they are making airguns in the first place says to me that they are satisfied with the airgun market. Why don’t they just offer solutions themselves, and add to their market share?

    I guess the best example of what I am suggesting is demonstrated by an air pistol that I purchased a few years ago. We are all aware of the “droop” problem that is encountered when using optical sights at close range. That’s a big reason that we are discussing adjustable mounts today. This particular manufacturer built the droop correction right into the top of the receiver. Brilliant! When an optical sight is mounted, it points down at just the right angle for the sight line of the optic to intersect the point of impact at ten meters while adjusted to its center of its range. And it didn’t cost the manufacturer more money to make it happen. Just good engineering from the start. They were going to machine the top of the receiver anyway, so they machined it at an angle, rather than defaulting to a line that is parallel to the bore. When I handled the pistol at the sales counter where I bought it, I noticed this feature. That prompted a very careful examination, where I found even more shooter-oriented engineering, so I put my money down. Like I said earlier, that was a few years ago, and I’ve been 100 percent satisfied with my purchase.

    I have only been shooting adult airguns for about seven years at this point, but learned early in the game that quality is worth what you pay for it. If there is one thing that I am definitely NOT interested in buying, it is a product that has a known problem that the manufacturer is aware of and won’t fix. In my mind, this whole issue of proper alignment of the scope rails is a combination of failed quality control and misdirected cost cutting. High quality adjustable mounts are a solution that we are forced to consider, because so few airgun manufacturers are considering their customers as part of their business plan.

    - Jim in KS

    • Jim,

      We could have a VERY long conversation about this, but the short of it is — most airgun manufacturers have very few people on staff who know anything about airguns. They know how to make them, but they don’t know how they work, nor do many of them really care.

      Crosman and AirForce Airguns are 2 exceptions.

      Several years ago I had this exact conversation with Diana’s Vice president of Marketing, when I met her at the SHOT Show. She told me in perfect English (that was far better than mine) that Diana was not concerned about the performance of scopes on their airguns, and because their breakbarrel rear sights were always mounted on the barrel with the front sights, drooping wasn’t a problem.

      The Diana 350 Magnum had recently hit the market before we had this discussion, and it is the one breakbarrel that Diana makes that doesn’t have any barrel droop. So Diana did change things. They just won’t admit it, nor will they change the tooling on any existing models.

      Change will come, but it will come slowly. I hope to have the patience to wait for it.

      On the flip side, things like this create big opportunities for companies that want to get ahead.

      B.B.

  • Gunfun1 Says:

    Sounds to me like somebody needs to invent an adjustable scope riser.

    • David Enoch Says:

      “Sounds to me like somebody needs to invent an adjustable scope riser.” ….or a precise barrel bender! Although it sounds all wrong, the more you get into it, making a barrel point to where a centered scope points sounds like a better and better solution.

      Adjustable mounts have to pivot and pivoting puts all the force on one small spot. Add to that a large scope and heavy two way recoil and you have a recipe for trouble.

      David Enoch

      • Gunfun1 Says:

        I was thinking something like our precision vises at work that adjust for angle grinding.

        The riser would be a 2 piece system. And would adjust for elevation and I guess windage if you wanted also.

        The front riser would mount to the gun and would pivot front to back. The scope ring would then mount to the front riser that pivots.

        The back riser would be 2 pieces: a bottom part that would mount to the gun and have a threaded set screw that would attach to the top part that the scope ring would mount on. The top part of the riser would have a pin going through it horizontally to the left and right. That pin would be threaded for the set screw to thread into it.

        When the scope gets mounted and you adjust the set screw in the back riser the back of the scope would raise up and down and the front mount would pivot and not bind anything.

        Something similar could be done for the windage adjustment with a set screw on the back riser also.
        The more precise the tolerances would be held the better it would be of course.

        The reason for the comment about the adjustable riser is possibly have a more precise way to adjust your scope in addition to the erector setup.
        And since the scope manufacturers don’t seam to be worried about the erector spring problem they for sure probably ain’t worried about putting time, and money into a riser project that maybe only 500 to 1000 people might purchase.

        But what would happen if somebody would start making this kind of aftermarket stuff for airguns and it did work. I bet somebody could make some money. And maybe catch on to the firearm world. That’s what happened in the Muscle car era. Isky, Mondello, Edelbrock and the rest started a aftermarket revolution for hotrodders of the day and still to this day.

        I would like to see the manufacturers or somebody step up the game for us air gunners. Now. Not in another 5, 10, or 20 years from now.

        All I can say is (Time Will Tell).

      • David,

        A properly designed adjustable mount doesn’t put any strain on the scope. It holds it straight. But the key is, it must be properly designed.

        B.B.

  • Matt61 Says:

    I would think that adjustability for the scope mount would impact its stability at some point. It’s sort of like the way joints in the skeleton are points of weakness that allow movement. You can have rigidity or you can have movement but you can’t really have both.

    I saw one rifle custom built for long range shooting that had a mount that slanted 20 degrees down towards the barrel. That would help for long range but is not a universal solution.

    I’ve never seen those markings on the turret that show how far a scope has been adjusted. That would be really useful. One really useful statistic would be a rough idea of the maximum number of clicks in a scope. After turning and turning, I sometimes have no idea where I am in the range. I do suspect though with my airguns shooting at 5 yards, that I must be at the very limit of their adjustability. I’m probably lucky to be on target at all.

    Here’s one scope mishap that I haven’t solved. It has to do with a 40 mm objective scope that I bought for my Anschutz. The brand is Centerpoint. With what I believe are medium mounts, the objective just clears the barrel. Perfect. The first time out, I couldn’t adjust the windage onto point of aim. I switched the rear and front scope bases for each other and everything was fine. Then there came a day when I was zeroed at 50 yards and switched to 100 yards. The point of impact was now low and I could only adjust it within two or three inches of point of impact but no higher.

    One of my objectives at my last shooting session was to retest the scope. I mounted it at the identical place on the receiver with the knobs adjusted the same way as last time. Now at 50 yards, I was way off paper to the right. I dialed like mad, and somewhat to my surprise, got zeroed before running out of adjustment. I dismounted and remounted the scope in moving to the 100 yard line (because of all the stuff I was carrying). Now, I was again off paper to the right and had to dial away although I managed to get zeroed again. The state of the erector tube would probably make me shudder. What the heck is going on? How I wish B.B. were on site to see that I am not making this up and to figure out what what the problem is. I’ll give it another try when I take out my Mauser in a couple weeks.

    Matt61

  • Mark N Says:

    B.B.,

    Can you tell us about the Conetrol rings and mounts? I have never hear of them being used on an airgun but I don’t know much about these things. Are they appropriate?

    Thanks,
    Mark N

  • John Says:

    I have a scope that is a bit of a problem. It’s a Bushnell. Not a expensive scope, but not a bottom of the barrel scope either. For some reason no matter what I do with it the thing is never ever on target. I build a proper sight picture, watch my breathing, trigger squeeze and have the cross hairs right on target. I take my gun off safe, pull the trigger and the shot totally misses the target. I’ve centered the scope. Set it with a laser, and I know the gun is good. My condor has never failed to put the shot where I want it with any other scope. But that Bushnel just does not do the job no matter what gun it goes on. I’ve tried it on my marlin 60 custom, AK47, AMD65, Mossberg 100ATR, and every other gun that takes a scope. It simply causes my shot to be off on every gun. I suspect it needs to go in the trash and I need to start buying optics instead of more guns I won’t use that are poorly made in china. Had another gun fall apart in my hands today….again, made in china.

    • Fred DPRoNJ Says:

      John,

      I have a couple of Bushnells and they have given me very good service so far. From your past posts, the impression I have of you is you’ve forgotten more than I know so I won’t question you on how you sighted in your scope. I suggest you go to the Bushnell website and find the number for customer service and see if you can send it back to them. They are typically very good about servicing or replacing a scope that has gone bad. It can happen even with the best of products. Sometimes something inside has let go and you now own a very expensive castenet.

      Fred DPRoNJ

      • John Says:

        Right and wrong. I was raised on iron sights. I was also traind by the military to know rifles inside and out. Build then, service them, fire them. I know just about every pin and spring in any given modern service rifle that I have ever run across. I know ballistics, and many many other things gun related. But one part of what I am missing that I am learning at a very fast rate is scopes. I never had much need for them until a few years ago as I aged and my vision began to deteriorate as all our eyes do when we get older. So now I’m an old dog learning some new tricks. It can be done as long as we open ourselves to accept the reality of life. I’m getting old now and I’m not afraid to call it the way I see it. I’m old. So I need new things to keep me behind the trigger and hitting my targets.

    • BG_Farmer Says:

      John,
      Don’t waste ammo on a bad scope! I’ve been there and done that…

      Most of these companies have a lifetime warranty and will repair or, much more likely, replace a scope if you send it in. It costs just a few bucks to mail them the scope and chances are pretty good you will get a good one in return. Most of the cheap scopes can be good (the designs are pretty standard), but they don’t have the QA/tolerances that more expensive brands, so you have to work to make sure you get a good one (or pay more, which is a viable option also depending on how critical the task is). I’ve always liked Bushnell — the optics aren’t that great, but they seem to hold zero pretty reliably; that makes me happy, because I think I can see where they compromised to meet the price point. Of course, I’ve had good luck with Tasco, as well, so maybe I’m lucky :) !

      • BG_Farmer Says:

        Sorry, Fred — you were writing at the same time! Great minds, I suppose.

        • Fred DPRoNJ Says:

          Hey, I might not be a better shot than you and as I recall, you are into astronomy (I get lost after spotting Orion’s Belt) but obviously I can type way faster than you! And being a one time electrical enginner (at least the diploma says so), I can handle the math capchas with aplomb!

          Fred DPRoNJ

          • BG_Farmer Says:

            Great, let’s make the captchas hex, octal and binary :) ! 64 bit operands ought to cut down on spam…

            For astronomy, if you try the book “Turn Left at Orion” and don’t impress yourself, I’d be amazed. It is perfect for learning starhopping with a small scope and learning observation skills. And before you tell me NJ is light polluted, let me say I worked through most of that book from a tiny backyard in Sunnyvale CA, surrounded by a few million lights. Not to mention being under a flight approach to San Jose — I about lost my continence when an Airbus flew right through my 125x FOV; big change from a dim nebula to a blinding white airliner with lights on!

      • John Says:

        I know everybody always grumbles about the scopes that come with gun packages. I’m thinking of things like my Big Cat. The scope is pretty junky. But I have fairly decent results with the Optima scope that came with my Hatsan 125th on my Condor. The few scopes I have get swapped around a bit from gun to gun depends on my needs. I have a second Optima scope that goes between mt Disco and my Marlin 60. Right now it’s on my marlin 60 since my disco is out of commission again for a leaky valve. I’ll get around to replacing it again some day. I need to start buying scopes and optics.

        • Fred DPRoNJ Says:

          As I said, you’ve forgotten more than I know. And if you think your eyes are bad, consider that if I lose my glasses, I can’t see the rear sight on my rifle, never mind the front. Curious if the military would have taken me back during the Vietnam War (2S deferment). You can go nuts trying to zero a scope that refuses to hold zero. Most of the scope/rifle packages one buys include a real bottom feeder scope. I have one sitting in my draw at home that refuses to hold zero that came with a Benjamin Nitro package. I don’t know why I don’t throw it out. Crosman replaced the scope, no questions asked. The scopes we get for our air rifles and that PA handles are very practical and adequate for our shooting which is typically no farther than 50 yards. We airgunners just have no reason to pay $800 since we aren’t shooting out to 200 yards. If you’re competing, that’s a different story. Then the best glass you can afford is recommended.

          PA sells a bunch of decent scopes that you can swap between rifles – for $100 to $150- that I have been very happy with. All kinds of eye relief, diameters, objective lens sizes and overall scope length choices.

          Good luck.

          Fred DPRoNJ

          • John Says:

            That’s all a matter of perspective. I don’t know how much you know about guns. Depends on what guns we are talking about as well. I know springers, pumps, co2, and pcp guns and can repair just about any gun however I choose not to work on springers. I can build you just about any powder burner or airgun you like and teach you to shoot with some degree of accuracy. I can make you almost as competent as I am in what I do as long as you have some mechanical ability. But scopes are still fairly new to me. As I got older and my eyes have changed I have had to begin to adapt from iron sights to scopes. I’m learning to adapt from iron sights to a scope. Your cheek weld is different and you have to pretty much retrain your body to get in behind that higher scope than you do on iron sights if you’ve been on iron sights your entire life. So even though I know guns inside and out down to the last detent and spring, I might as well be a new shooter since I now need to relearn to build a different sight picture.

            I’ve always worn glasses and yet I impressed the military enough to be invited to a different training than I signed up for. I have no regrets in that. I have discovered through life experiences despite any handicap you may have you can find a way to do anything you want to do.

    • John,

      While there is no way of knowing what is wrong with your scope, the fact that you have tried it on different guns of known accuracy tells me the scope is a bust.

      It happens to every brand.

      B.B.

  • David Enoch Says:

    BB,
    The two most common issues I have with scopes are:
    1. Weak erector tube springs on older scopes such as the Beeman 66 R
    2. Short and narrow eye relief on scopes.

    When I first got into airgunning I chased pellets with a Beeman 66R scope for weeks. I finally moved it to another gun that didn’t require going far from center and the scope worked great. It wasn’t until years later that I finally understood what had caused my frustration. Seriously, if you are having trouble with a scope and rifle combo, changing up the combo is often the easiest fix.

    Being left handed causes many problems which we learn to overcome. One of them is that rifle butt stocks are often cast to the right to put a right handed shooters eye right behind the scope. If a lefty shoots that scope he is already at a disadvantage in that his eye is too far to the right due to the cast. You need a very forgiving eye relief on a lot of rifles to get it to work right. Also, some rifles scope mount grooves, magazines, and loading ports make us put our scopes in less than perfect locations. This also makes eye relief critical. The longer and wider the eye relief is the more forgiving it will be to our head location in relation to the scope.

    David Enoch.

    • David,

      I once owned a Beeman 66R scope, too. Terrible glass! I returned mine, as it couldn’t be used. It is as cheap a scope as ever was imported from China.

      Of course Beeman may have bought them from different makers over the years. Some may have been good. I just never saw ine.

      B.B.

  • Pop's SLR Says:

    Thanks for the further information B.B. and all who commented. I have really enjoyed fixing my scope to be in line with the axis of the bore. No more shifting poi from right to left the further my target is away from me. I found the right pellet as well. H and N FTT. With all i have learned from this blog i went out yesterday and brought home dinner. Thanks to all.

    Question…I have a lovely swift duplex scope that i can extrapolate accurate aim points out to 40 yards with. However, my SLR when rested will shoot 1” 7 shot groups at 65 yards if there is no wind. I think a mill-dot scope is in order. Any suggestions? Is the air-force mill dot scope a good choice? I may Select another swift with a mil-dot reticle. Thanks for your time. Great blog and wonderful comments!

    • Gunfun1 Says:

      I like the Hawke half mil dot scopes. And Hawke also has the Chairgun Pro program that allows you to map a recticle for hold over for different ranges and the type of recticle you have.

    • Pop,

      Both the AirForce and Swift scopes are excellent values. And mil dots are what people use for situations like you describe. It would be hard to make a mistake, going to a mil dot.

      B.B.

  • Mel Says:

    Benchrest shooters often block their scope adjustments and use adjustable scope mounts. The reason behind this is how a scope manages recoil: The internal erector tube moves forward during the shot, and a spring re-sets it. This works precisely enough for most applications, but Benchrest shooters need the absolute best in accuracy.

    Seveal small companies make windage and elevation – adjustable scope mounts. These are made to very high standards – they are marketed to the most demanding shooters out there – and therefore very costly, and not suited to airguns for a variety of other reasons.

    • Gunfun1 Says:

      The adjustable scope mounts still seem like a good idea to me. And price is always a issue. But it is the same way in the drag race world and other sports also.

      But it is nice to know that a option is out there to be had and tryed.

  • dogman Says:

    As far as dealing with barrel droop, I feel the easiest way is to use a 11mm adapter to weaver mount, and then use the Burris Signature Z-Rings with the inserts. Windage adjustment problems can also be dealt with these. In my firearms I center the scope within it’s adjustment range and then attempt to sight in gun with the inserts (I use a bore-sighter). When I get close I call it good for the mounts and move on with my sighting in procedure at targets. I just wish they had 4-screw rings. When dealing with barrel droop problems in airguns before the Burris off-center insert option I used shims, often to excess, but felt I had no other option. Now with these 11mm to Weaver adapters available I can try a trick I used to utilize for firearms too far out on the up and down adjustments. I would just file/grind the front scope base instead of shimming the rear ring. In order to deal with possible bending of the scope tube I would lap the rings. But I didn’t use one of those fancy kits. I just bought a 1″ iron bar from the local iron works and used valve grinding compound. It took some elbow grease, but since I was usually grinding out soft aluminum it was doable. One of my gunsmith books says you cannot grind out the aluminum rings this way. Lucky for me I was doing it before I read this. Actually I was doing it before I ever even saw one of those lapping kits for sale, and no one was writing about it yet. Of course this does not correct East & West issues, but has anyone ever took this approach for airguns? Any opinions? Suggestions? JG

    • twotalon Says:

      dogman

      I never used a lap for that particular reason, but I have lapped a couple sets of mounts to get them nice and straight so I could install scopes with no twisting or bending. I did not do any before/after comparison for P.O.I. changes.

      twotalon

    • JG,

      If anyone is lapping rings for airguns they aren’t talking about it very much.

      B.B.

  • dogman Says:

    First off I have to say your blog reply (or whatever it is called?) for communication seems like it most often works very well. Hats off to everyone as a group. Several years ago I got involved with something similar on another subject. Whew! What with the hotheads and strong opinionated SOB’s overpowering it all, it made for a bad experience and turned me off to ever getting involved again. You folks are definitely on a much more positive and useful track.
    As far as Twotalon’s reply, I would not expect the lapping, no matter how aggressive, to change POI much. What I was trying to convey was after my filing and grinding of the upper surfaces of only one the scope bases (which definitely did change POI), some lapping seemed to be in order. But now instead of just overcoming a bit of misalignment of the base screws or gun surface inaccuracies, I would be overcoming many thousands of inches created by the filing off of just one of the bases. This involved quite a bit more lapping and became almost a grinding operation in itself. Weaver bases are pretty soft and so I suppose some filing on the edges could also be done for side to side problems. I only played with the right/left changes a little bit so don’t feel qualified to say that works too. Of course all filing of the bases (up/down or right/left) needs to followed with the fairly extensive lapping, which was what I started out referring to. Some of the Weaver style rings are quite inexpensive and so it is not such a risky investment. Realizing you might ruin them, or at least make them useless for any other gun. The Burris Signature rings are around $35 plus extra for inserts. Between firearms & air rifles I have a lot of scopes to mount. Not all of them are upper end pieces and even after the Burris option became available I was sometimes just looking to save a few bucks. Lapping as Twotalon refers to ,as it is advertized and often written about, always seems like a good idea to me. But I’m still interested if anyone else went down this “thinning just one base and then lapping” road? Thanks ahead of time for any thoughts or experiences out there. JG

    • JG,

      Welcome to the blog. We don’t allow the flaming of people here, and we have lost a couple readers because of it, but we have tens of thousands of active readers and we are growing larger all the time.

      You are the second person to mention the Burris Signature rings, so I think I’ll look into them. If they are as good as all that, perhaps Pyramyd Air should consider stocking them.

      Thanks,

      B.B.

  • Pancanaka Says:

    BB,
    Just in time. I have my scope problem recently. I didn’t remember you’ve been rolling a series on scope problems until today. Hope someday you’ll cover my issue on your writing.
    My Hawke Sport-HD AO reticle seems canting clock wise for every shot I’ve taken with my springers. Further angle i got for every shot i took. I believe I didn’t put the erector tubes under too much stress because I’m sure I didn’t turn the knobs over 3/4 of its capacity. I believe Hawke sports scopes are rated for spring piston air gun recoil too although they manufactured somewhere in China which I think it’s affecting their quality control. What possibly happen? Is it any DIY solution to get it fixed (I’m aware there will be a major operation involved and sacrifice taken from wasting the filling gas)? Well it’s broken. But the warranty doesn’t cover up to my country and I hope I can still use it for my pneumatics.

    • Wulfraed Says:

      Rotated reticle is what my RWS/Diana m54 did to kill a scope.

      I don’t think anyone has certified a scope for rotational torque — only for the reverse recoil of piston guns…

      But since a spring adds a rotational twist, not just the forward slam, I believe it is possible that the tube carrying the reticle could rotate as the gun “twists” while firing. This is the major advantage of “nitro pistons” — all forces are linear.

      One would need to have identical guns — one with coil spring, one with gas spring — to test the hypothesis.

      • Pancanaka Says:

        Wulfraed,
        Interesting hypothesis and almost never find it else where. If it is exist, why some guns exhibit the phenomenon when else not. What cross in your mind that Diana 54′s spring would have tendency to rotate ferociously? Is it the stroke length?

        • Wulfraed Says:

          If the piston fit is such that it can rotate as the spring expands, you’d get the piston torquing one direction as the receiver gets torqued the other way. How the ends of the spring fit against the piston and receiver could also have an effect — smooth finishes that can slide vs a sharp edge the digs in and transmits the torque to the rest of the system.*

          And, in a way, the m54 is one of the earlier “magnum” pellet guns, designs may have been tweaked some (mine is a T01 trigger group, which I believe also means a different design in the piston mechanism that holds it cocked).

          * You should see the design work that went into the SBIRS Geo mirror aiming motors as they had to minimize torque to the satellite (which would have thrown off the pointing accuracy of the other mirror). The motors are designed to spin opposite to the mirror direction — instead of being fixed to the satellite frame the outside of the motor is on very fine bearings, while the mirror is attached to the motor shaft. The motor mass had to be designed to counteract the mirror — instead of the motor stepping the mirror by x-degrees rotation, the motor has to step 2x, as each step has half the effect on the mirror. (these are stepper motors that only have to move a few degrees each way to aim the mirror, not continuous spinning motors)

    • Pancanaka,

      Scopes break. They break on firearms as well as airguns. I have had the rotated reticle, too.

      The one bad thing a person can do mis over-tighten the scope cap screws with steel rings and squash the scope tube. That usually starts the breaking process. But often they break for no obvious reason.

      B.B.

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