Uncle Jock’s Screwy Theory of Reducing Springer Hold Sensitivity

Monday, November 22, 2010

Boy, if you want to get airgunners “lit up” on a topic, try discussing springer hold sensitivity. Some professional spring gun tuners will tell you there’s no such thing as hold sensitivity in a spring-piston air rifle, that there are only shooters who don’t know how to shoot springers properly. On the flip side, there are experienced spring gun shooters who will tell you that the aforementioned professional tuners are in desperate need of a physic.

Whether or not it is me or the gun, I can tell you there are times when I can’t shoot a spring-piston air rifle worth a darn and other times when I am pretty good. In other words, sometimes I’m a hero, and sometimes a zero. (By contrast, I shoot well with pre-charged pneumatic or pump-up pneumatic airguns almost all the time.)

Lately, I’ve been working on a theory of how to reduce the apparent hold sensitivity of springers. But before we get into that, a little background.

The thing that can make a spring-piston air rifle difficult to shoot well is the basic powerplant within it. When you cock a springer by pulling the barrel or a side lever or under lever back until it latches, you are compressing a spring. The spring remains under tension, like a sprinter in the blocks, until you pull the trigger. Released from confinement, the spring lunges down the compression tube, pushing the piston in front of it. This causes recoil toward the rear of the gun. As the piston reaches the end of the compression tube, it bounces off a wad of compressed air in front of it (at the same time air squirts through the transfer port, launching the pellet down the barrel), causing recoil in the opposite direction.

Now, here’s the really cool part: all this thrashing around of spring and piston within the rifle, the forward-and-reverse whiplash recoil, all of it happens before the pellet leaves the muzzle. (In a precharged pneumatic, by contrast, when you pull the trigger, a valve opens, air squirts down the barrel, driving the pellet toward the target, and there is a teensy amount of recoil to the rear. It’s all very dull, boring, and generally accurate as the dickens.)

It’s been my observation that if you inadvertently hold a springer with more pressure on one side of the forestock than the other (as many of us do), the gun will tend to jump away from the side with more pressure when the shot is triggered. I saw this graphically demonstrated with a Beeman R1 in .177. I had a 3-12 scope mounted on it, and it would shoot little tiny groups at 20 yards. The following day it would shoot little tiny groups, but half an inch away from the location of the previous day’s groups.

It drove me nuts. So one day, I took off the scope, mounted a peep sight and consistently shot little tiny groups in the same location all the time. I spoke with Steve Woodward about it, and we came up with a theory. First, when a springer jumps away from unequal pressure on the forestock, it tends to rotate around the center of gravity on the rifle’s long axis. Ideally, you would like the gun to rotate around the bore. But when you mount a scope on the rifle, you raise the center of gravity, which tends to exaggerate the movement of the bore and throw your shots off. The bigger, higher, and heavier the scope, the more you tend to throw your shots off (that is if you are not shooting with a perfectly consistent “hold”). The peep sight worked because it was light and low.

So, what to do? Well, here’s my working theory: to reduce apparent hold sensitivity in a springer, mount the lightest scope you can, and mount it as low as you can. This should raise the center of gravity as little as possible, resulting in more consistent shooting. I have tried this with one of my springers and it seems to work

But this is not written in stone; it’s just an idea I have had that seems to make sense. So, if you like, try it with your springers and let me know your thoughts.

Until next time, aim true and shoot straight.

–         Jock Elliott

23 Comments

  1. M. Albrecht,MD. says:

    I concur with your observations. My HW 55T is equipped with a peep sight and consistently very accurate at 10M. My R7 has a compact Burris 3×12 scope and a low mount,and ideal combination for best accuracy!
    M.A

    1. Jock Elliott says:

      MA,

      Good to hear from you. Also good to hear that your experience squares up with mine.

      Maybe my theory isn’t so screwy after all.

      Thanks for the comment.

  2. Jock Elliott says:

    Mark Kauffman emailed me with the following:

    Hey Jock,

    In response to your theory of springer sensitivity and center of gravity relationship, I have another idea that may go along with yours.

    When you mentioned that you would like all of the weight to ideally rotate around the axis of the barrel, you are adding weight (the scope) to the top of the gun…..period.

    Have you thought of adding an equal amount of weight, via custom stock, knee riser, or just plain lead weights, to the underside of the gun?

    My TX-200 shoots phenomenally well with the addition of a Steve Corcoran stock, to which I also added a knee riser. This would counterbalance the weight of the scope on top. More mass weight also tends to dampen the entire firing impulse with less felt recoil.

    To which I say: Mark, that makes sense to me!

  3. Suresh says:

    Thats a good observation. I unmounted the scope from the HW 80 recently. its a CP 4-12*40. Now the Weight is reduced , Iam feeling very confident and convenient to shoot with the open sights or other wise like ur idea , i am happy to fix my daisy 3-9*32 in it. No more big scopes for springer!

    1. Jock Elliott says:

      Suresh,

      Thanks for your comment. I’m glad it’s working for you!

  4. Larry Pirrone says:

    Jock, I shoot field target with a TX 200. I added about 30 oz of lead to my stock. Not only to rebalnce the for/aft balance (moving it rearward) but to counter the top heaviness. I put 10 oz on the sled of my riser and taped 20oz on the bottom of my pistol grip. This made quite a difference. When I sat down to practice yesterday for some of the shots I placed a pellet on the turet and shot with my normal FT hold and the pellet did not move at all. Part of it is just more mass to counter the moving mass in the action and part is lowering that mass so much. I also have a mercury recoil reducer on the way that will create for/aft damping (controversial I know)

    With the weighted stock I shot 25 meter benchrest the other day (692/750) and scored 94% of the high pcp score. I was shooting 11.5 fpe and he was shooting 30. It was quite windy and raining.

    I am not sure that this completely eliminates hold sensitvity but it does reduce it. I still have to concentrate on all of the fundamentals and watch side pressure.

    Larry

    1. Jock Elliott says:

      Larry,

      Thanks for your input. So it appears that weight matters and where the weight is located also matters!

  5. Parallax says:

    I totally agree with you Jock. Every time I shoot a springer with open sights, I’m far, far more consistent. My groups may not be quite as tight at the longest ranges, but the rifle will consistently print cloverleafs and clusters over and over again out to 35 yrds and the group sight-in location will never shift from day to day. I can just pick the rifle up any particular day and the POI will be in the exact same spot.

    I think 90% of folk’s POI whoas with springers lies in the application of the scope. Either a mounting problem or scope problem. Not using good enough quality mounts or scopes and getting far too big and too heavy of a scope with mounts too high all lead to major problems and constant shifts in POI. It’s either very harsh on the mount and scope in that situation and things keep moving around and loosening, or as you stated, it makes the rifle MUCH more sensitive to how you hold it.

    One of my favorite combos for scoping a spring rifle is the little rugged, small and lightweight Leupold 3-9×33 EFR on LOW Sportsmatch 2 piece or 1 piece mounts to get it as low to the bore as possible, keep the weight down to preserve balance and nullify hold sensitivity.

    Once I’ve taken my time to degrease all the mounting screws, set everything up snug and even and get it sighted in, the POI stays right there in the same spot with no worries from day to day and 9x magnification is MORE than enough for spring rifle range applications.

    1. Jock Elliott says:

      Parallax,

      Thanks for your comments. It appears that maybe my theory isn’t so screwy after all.

  6. Larry Pirrone says:

    Jock,

    After I posted on the weight being added to my tx iIshot an FT match. Shot the worst score that I have shot in a year. Not sure what the cause was but I had a very difficult time. May not have been the added weight or it may have changed the way the gun should be held.

    back to the drawing board.

    Larry

    1. Jock Elliott says:

      Larry,

      I’m sorry to hear of your difficulty. Keep me posted on what you discover.

  7. BigAl says:

    A lot has been written about this subject and it is well known there are many variables to take into account with springers. I shoot 100 yard targets with my Remington NPSS and found several factors affecting accuracy. Settling on the type of pellet your gun seems to shoot best is number one on the list. After that, it is all up to your hold and calmness when shooting. I found the “no grip” forearm rest works best. I also do not push the stock into my shoulder gently rest my cheek on the stock. Letting the gun do it’s own thing while simply supporting it and concentrating on the target in the scope works for me. I am not saying it works every time or for everyone, but try to take note of all the various hold methods, settle for what works for you, and then experiment with perfecting it.

    1. Jock Elliott says:

      BigAl,

      Thanks for the comments. I find that sometimes the “free recoil” technique works best, but with some guns, the Ninja Death Grip is better.

  8. Scott says:

    jock, can you tell me how to start a airrifle club in the Rochester n.y. areas this
    City has not a thing around here for a air rifle Club.

    thank you.

    Scott M.

    1. Jock Elliott says:

      Scott,

      I don’t have any experience in starting air rifle clubs (or any other kind of club), but maybe one of the readers of this blog can chime in with some helpful advice.

  9. G. Austin says:

    I couldn’t agree more. I had an rws 350 magnum 177 and tried four mounts and three scopes. As soon as I switched to the factory open sights I was golden. The gun shot so reliably that I trusted it again. I always thought it was a lockup issue or unreliable scopes. This blog post explains how the center of gravity affects the gun and makes so much sense. I might try a springer with peep again. Thank you!!!!!!!

    1. Jock Elliott says:

      G. Austin,

      Thanks for the kind words. All I can say is that the theory seems to work out in practice for me.

  10. Jez Saunders says:

    Read with great interest and would explain a lot of inconsistency I have experienced over the years with my springers. Lighter scopes for springers is the way to go. Getting the center of mass below forend will be my next endeavour . Jez

    1. Jock Elliott says:

      Jez,

      Thanks for the feeback!

  11. Shooter McGavin says:

    Imho, I’ll believe an experienced tuner over an experienced shooter any day of the week. A tuner has something that most other shooters don’t have, a better understanding of the guns themselves. Accuracy stems from the gun itself. You can put a piece of crap gun that nobody can possibly shoot accurately in the hands of an “experienced shooter” and he’ll probably just tell everyone the gun’s “hold sensitive” instead of spending the time and effort to figure out what’s causing the inaccuracy and correcting the problem/problems if at all possible. There’s a laundry list of things that can be passed off as hold sensitivity but have nothing at all to do with that. For example, what you just mentioned, the scope. Most scopes can’t handle a spring rifle and the zero will wander around like a drunk. Many airguns have barrel droop and if you don’t shim even a good scope correctly then they wont hold zero either until you shim it up right because until there’s enough spring pressure against the erector tube it’ll be incapable of holding the reticle in its zeroed position.

  12. Shooter McGavin says:

    Albert Einsteins parents thought he was retarded haha!
    Here’s one of my favorite quotes from a tuner.
    (Spring gunning 101)
    “Here it is all you need to know about springers in one short paragraph.
    Only care about velocity? Run a spring on one sloppy guide spaced to the max and no lube.You will get velocity and the gun will shoot like a bucket of bolts. Put two tight guides on it and a correct tight fitting seal, with some lube and it will shoot like a dream if the receiver or comp tube is true. Should be common sense. Chrono a gun after a fresh repair or tune. Why bother? It’s not going to tell you much. We as well as others strived in the mid 90’s to present these facts to the Internet world but since the “old timers” no longer do forums, it’s all been lost.”

    The two guides he’s talking about is the bottom spring guide and the piston itself. He also said it’ll shoot like a dream if those requirements are met. That is precisely true IF the barrel is perfectly fine also and IF you feed it the ammunition that it likes the best and IF you hold it by the stock to shoot it.

  13. Al says:

    I wanted to say that this article is 100% True. After putting a big scope on my Diana 350 I realized that open sights were actually more accurate. then I bought a two piece low mount with stop pin so the scope almost touches the top of my rifle. the gun does not jump around anymore and it is far less hold sensitive. At 8 meters pellets go through the same hole. and one more thing if you get a two piece mount, place them as far from each other as possible, this will also help by reducing the leverage.

    1. Jock Elliott says:

      Al,

      Thanks for the kind words!

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