What the heck is going on with my Diana?

[eatsShootsAndSleeps]

That sine wave patterns sure tweaks my interests. Sounds at first like there must be something circular involved. But it could also be a very, very slow change in shooting behavior that works its way out and then back. So hard to tell. Hope you get it sorted.

[RedFeather]

Looked carefully at your targets, again.  Noticed that most are right on vertically.  That is, they are in line with the bull most of the time (with a slight shift to one side but not like a flier).  It's as if your gun is shooting high, then low for a bit, then high once more.  But the variance is almost steady throughout each string.  My money's on the scope.  You wouldn't be able to hold such consistency with a bad seal.  Consider that your seal would have to be leaking consistently (as in when you zeroed the bulls), then tighten back up for a string or two for the high shots, then leak consistently once more to bring the poi back down.  It could also be due to a slight change in your cheek weld.  Is the eye relief comfortable with the new scope or do you have to "crawl" the stock a bit?  Still, looks like something mechanical going on with that scope.  As said, the CP's have been known to be spotty.

BTW, with such a tiny target (dime sized in full?) and at 16X I imagine it's not that hard to throw the poi off through slight movement.  How bright is the scope at 16X?

[pappa]

On a springer you should always support your gun with your hand, no matter what kind a of rest you use.

I can't totally agree to this supposition. My sight-in rest is atop a tripod with a V shaped rest with 3 inches of double layer soft egg crate foam on top. I can get a very decent sight-in with a brand new rifle on this in 5-8 shots and then start immediately to get dime sized groups at 10 yards. On a well broken in rifle and a good tune-up, with this rest, I can  regularly get ragged one hole groups at 20 yards but cannot get close to this with a hand hold. Although I am a fairly good varmint killer with my ARs, I can never duplicate with my hands (the artillery hold) as well as on that soft foam rest.

[GunnerAl]

Sorry if I cover some ground that other may have already...

If this problem is happening consistently in this up and down motion and just keeps happening over and over again rythmically then it suggests something has come adrfit and is also moving rythmically, like  mounts or some other mechanical device, but to repeat like it does would seem to indicate something is moving back and forth or up and down or side to side etc. Look for scrape marks in the bluing or painted surfaces in and around the scope mountings etc.

How many shots does it take to complete one whole cycle - that point at which you can see the cycle starting all over again..??
Does this happen exactly in the same manner per complete cycle - roughly the same number of shots per cycle etc..??

Definition of a "cycle" just to clarify, eg = The POI is dead on the bull, then begins to climb, topping out, then begins to fall, falls past the bull, keeps falling, bottoming out well below the bull, then begins to rise, eventually back to the bull... That I call "one cycle",, where the POI will once again begin to climb...

Can you see a pattern happening whereby you get a continual rythm..?? If the cycle is getting bigger each time or smaller each time, then it may be that it is building up to some sort of final event and may eventually result in something giving way, coming completely adrift or breaking etc. If the cycle is the same each time, then it appears there may be an answer, depending on just what really is happening... I know I am stating the obvious but all you have to do is to find that cause...

The first place to start is tightening all those screws - for-end, trigger guard (screw into the gun), scope mounts, scope rings. I've seen quite a few similar problems in grouping that have happened through loose stock screws etc...

Good luck..!!

[tobar832]

   I had this same problems with my CP 4-16x40.  After buying 3 of them two are holding up well but one of the scope has this up and down movement too.  I've not documented it like you have but the up and down really rings a bell.
   Now I will lock- tite the small screws on the top of the dials and the small screws on the side of the dials also.   These go loose all the time with my B-26 and B-25.  Lately I bought two 3-9x50 Hawks, probably put the CP's in a draw
    When the scope started moving it was a slow process over 40-50 shots.  After trying and blaming the mounts it dawned on me it was the scope. 
     No problems with the Hawk scope they have been holding up good.

[Mr Sasquatch]

On a springer you should always support your gun with your hand, no matter what kind a of rest you use.

I can't totally agree to this supposition. My sight-in rest is atop a tripod with a V shaped rest with 3 inches of double layer soft egg crate foam on top. I can get a very decent sight-in with a brand new rifle on this in 5-8 shots and then start immediately to get dime sized groups at 10 yards. On a well broken in rifle and a good tune-up, with this rest, I can  regularly get ragged one hole groups at 20 yards but cannot get close to this with a hand hold. Although I am a fairly good varmint killer with my ARs, I can never duplicate with my hands (the artillery hold) as well as on that soft foam rest.

This has been my experience as well. I can get much better groups (see pictures above) using my front rest & not touching the forestock with my hand, than with the artillery hold. Besides, how could a rifle (an inanimate object) tell the difference between human flesh and bones and, for example,  a sock full of rice as long as it can move freely against the support?

[BenjiHunter]

On a springer you should always support your gun with your hand, no matter what kind a of rest you use.

I can't totally agree to this supposition. My sight-in rest is atop a tripod with a V shaped rest with 3 inches of double layer soft egg crate foam on top. I can get a very decent sight-in with a brand new rifle on this in 5-8 shots and then start immediately to get dime sized groups at 10 yards. On a well broken in rifle and a good tune-up, with this rest, I can  regularly get ragged one hole groups at 20 yards but cannot get close to this with a hand hold. Although I am a fairly good varmint killer with my ARs, I can never duplicate with my hands (the artillery hold) as well as on that soft foam rest.

On a springer you should always support your gun with your hand, no matter what kind a of rest you use.

That's what I was taught and it has worked for me.
If I zero a scope of a rest without my hand and then shoot off hand, POI is not the same.
Zero with my hand as support of a rest, POI stays the same off hand.

I can't totally agree to this supposition. My sight-in rest is atop a tripod with a V shaped rest with 3 inches of double layer soft egg crate foam on top. I can get a very decent sight-in with a brand new rifle on this in 5-8 shots and then start immediately to get dime sized groups at 10 yards. On a well broken in rifle and a good tune-up, with this rest, I can  regularly get ragged one hole groups at 20 yards but cannot get close to this with a hand hold. Although I am a fairly good varmint killer with my ARs, I can never duplicate with my hands (the artillery hold) as well as on that soft foam rest.

This has been my experience as well. I can get much better groups (see pictures above) using my front rest & not touching the forestock with my hand, than with the artillery hold. Besides, how could a rifle (an inanimate object) tell the difference between human flesh and bones and, for example,  a sock full of rice as long as it can move freely against the support?

That's what I learned and it have always worked better for me to support the gun with my hand.

[BenjiHunter]

The above post came out totally wrong.

[BenjiHunter]

On a springer you should always support your gun with your hand, no matter what kind a of rest you use.

I can't totally agree to this supposition. My sight-in rest is atop a tripod with a V shaped rest with 3 inches of double layer soft egg crate foam on top. I can get a very decent sight-in with a brand new rifle on this in 5-8 shots and then start immediately to get dime sized groups at 10 yards. On a well broken in rifle and a good tune-up, with this rest, I can  regularly get ragged one hole groups at 20 yards but cannot get close to this with a hand hold. Although I am a fairly good varmint killer with my ARs, I can never duplicate with my hands (the artillery hold) as well as on that soft foam rest.

This is what it should look like.

If I zero a springer of a rest without hand support and then shoot off hand, POI is not the same.
Zero with my hand as support, POI stays the same off hand.

[Bullit]

If you consider the skin's ability to slide on it's muscle, and then the next layer of muscle, as the next progressive absorber, you'll see the difference between it and a bag of rice.  Not to mention your clothing as another progressive layer.  Rest it on your forearm, and you'll see similar effectiveness.  Think of it as a 2 or 3 level progressive absorber, rather than 1 set level absorber.  I will say that I do use a bag also...with a folded up towel on it, to achieve 2 levels.

[thekid]

I must say, each person uses their own way to shoot.
If it works, the groups are satisfactory to you, then have it. Myself, I balance the rifle on my hand, I find this the best way for me.
It gives me extremely tight groups, but it may not work for others.

[pappa]

I think that we can all agree that what works for one doesn't always work for another. I get NO difference in POI whether using my foam rubber rests and using my hand in a hunting situation. I am sure others would not find this the case. We are all built different and hold and do things differently so there will always be natural differences between us. The only thing I was trying to express is that because something works for me, it isn't up to me to tell someone else that is the way they should do it. I probably didn't express my case very well so if anyone was offended, I apologize.

I DO, however, believe that we should all keep this thought in mind when we are attempting to help someone correct a problem by trying to get them to do things 'our way'. We should always attempt to see a problem from every perspective and try our best to not be dogmatic with recommending solutions.

[BenjiHunter]

The only thing I was trying to express is that because something works for me, it isn't up to me to tell someone else that is the way they should do it.

You're right.
My post, "On a springer you should always support your gun with your hand, no matter what kind a of rest you use."
It sounds like, do it or you will fail.
That is of course not the case.
It's just the way I was taught.

[RedFeather]

Regardless of his rest, he seems to be getting a consistent variance.  The POI's are as if the gun is shooting at one fps (sighting in on the bulls) and then a tad hotter (higher impacts) and then back down to the original fps.  Bad seals, changes in the "fuel" mixture, etc, cannot explain that since the variance seems to be consistent across the strings.  Why I opined that it is probably a sighting error and that points to the scope.  Could be cheek weld but I figure, if he can hit those bulls that well, he knows a thing or three about taking a consistent cheek weld.  The definitive test is to change the scope for another.  Until then, it's all conjecture.

BTW, shooting off the hand and then off bags will certainly change the dynamics of the shot cycle, just as moving the hand up and down the forearm will.  Springer dynamics - the eleventh circle of h3ll.

[Mr Sasquatch]

You guys gave me several ideas to try.  Thanks for your help. Basically, I'm reviewing every component in my shooting setup. One change at a time, checking for POI drifts. So far I've tried a different, softer front support, tightening those tiny screws in the scope turrets, dry parches through the barrel (again), deliberate & consistent trigger pull and the same location of the opposite thumb. So far, neither had any effect on the POI drift.

Tonight I checked the screws mounting the dovetail rail to the chamber - solid as a rock. Then I remounted the scope using loctite on some screws. I'll let it set for 24 hr and will continue my quest tomorrow.

If, after all these trials, the POI still keeps " walking", I'll replace the scope. I bought this one at Walmart with extra insurance so this should be easy.

[Mark 611]

I also have in the past bought scopes from Wallyworld and have nothing but problems with them! so I no longer buy scopes from them and try to buy a little better quality even if their Leapers their better then the scopes from there! JMO! I will make this point you cannot skimp on an AG scope especially on a springer!

[limbwalker]

Incidentally, I've had good luck shooting my spring and gas piston guns using a gel bicycle seat pad on top of my tripod for a rest that also "gives" like your hand would. 

It might be something to try.

John

[Mr Sasquatch]

Incidentally, I've had good luck shooting my spring and gas piston guns using a gel bicycle seat pad on top of my tripod for a rest that also "gives" like your hand would. 

It might be something to try.

John

That, or one of those gel-filled wrist support thingies used to prevent Carpal tunnel syndrome when using keyboards.

[Tater]

Incidentally, I've had good luck shooting my spring and gas piston guns using a gel bicycle seat pad on top of my tripod for a rest that also "gives" like your hand would. 

It might be something to try.

John

Good call John. I've done the same thing but I didn't even think of posting it.

Edit: Thanks for the reminder too, I'll have to try using it again.

[drewciferpike]

Coming at this from a mathematics point of view, those strings are WAY to clean to be completely random. There's definitely something of a cyclical nature going on, here. To really lock that idea down, do what someone else said and run some shots with your tightened screws, etc., and count the number of shots it takes to complete a full sine cycle (up from center, down from center, and back up to center). If you get 3+ cycles within 1-2 shots of each other, that's too clean, and variance is coming from a system with a limited axis or range of movement. Probably not you, looking at your "before" shots. Those showed the type of variability that one would expect.