I knew it was too good to last!

 My .22 Model-36 (A UMAREX "R" gun) is vertically stringing shots. Origonally the rifle was suprisinglly powerfull and still has quite a bit of power but the inconsistancy has rendered it unusable for the simple long range target chores it has. I did the usual tests, tight scope and rings? Best pellets?Even tried several different Scopes, then open sights? Yep, it's stringing it's shots!

 Like many of you, I am enamored with the long range capibilitys of my .177 caliber Model 36 and Model 40 and when I got the .22 Model 36, it's long range capibilitys were pretty suprising!

 I suppose that if you shoot only Crosman Premire and Beeman Trophy pellets (Both tight fitting and seeminglly high compression) that you press the .22 Powerplant beyond it's limits. Both pellets outweigh RWS offerings and perhaps taxed the spring for me? 

 When I eventually teardown the unwarrantied rifle and if I go with Factory replacement parts I'm sticking to  the most accurate shooting, light  RWS pellet it works with. If I choose an aftermarket kit, I may be able to go with other weight/Brands of pellet. I have had very good luck with both Factory replacement parts AND Maccari parts and I'm sorta torn between choosing the repair parts!

 I wonder that when old Dealers such as Beeman and Hy-Score ordered their "Batch Orders" just where did Dianawerk buy the upgraded springs? I have never gottten Diana or RWS to admit to my supposition of "Special Orders" but I have finally read of it elsewhere. It's funny that ya still can't find out which manufacturer makes the "Hot" European springs. Oh Well, maybe if you read German you could find em?

 Nevertheless, I now join many of you in reserching, planning, and scheming on building-up a powerfull .22 Diana. Gonna be a fun quest and I'm gonna take my time this winter doing it. I'm glad to have this wealth of information on .22 calibers here on the forum to shuffle through!

  ZVP

I would think variability in fps would account for stringing. Is the stringing consistent (i.e. - do the shots creep up in an orderly fashion?) How many shots in a group?

I would suggest you consider a JM Tesla piston seal lubed according to his instructions.When lubed correctly,broken in and mid weight pellets are used exclusively(JSB Express!!),your vertical stringing will likely vanish.Tesla's usually have to be fitted,but it isn't that difficult,just takes a little time and care.

"Service "springs" from gratitude".

1) Condition of seal between barrel and cylinder.

2) Barrel latch lock up mechanism and pivot screw, check for play.

3) Damaged crown (muzzle of barrel).

4) Partially loose retaining screws or cracked woodwork.

5) A couple of broken mainspring coils resulting in a gun that still shoots but with widely different piston velocities on different shots.

6) Damaged or worn piston seal that can display no.5's velocity differences.

If you are confident that your shooting technique is good and good pellets are used yet the problem persists, the remaining alternative is to strip it down,examine each area as you go and replace suspect bits.
HTH
David

The Diana guns have a ball barrel detent just like R7's and HW30's, and can have less positive lock up than guns with a chisel type detent. If the barrel is to tight, sometimes the ball type detent won't index correctly, causing vertical stringing. The barrel screw should be loose enough that the barrel will fall with it's own weight on a cocked gun.

If you shoot 21 grain Kodiaks, you may overtax your powerplant, but I seriously doubt that you are with the pellets you mentioned unless they are REALLY tight. You might want to try smaller diameter pellets like Crosman Points.

Just some thoughts.
Good luck!
Jeff

 Thanks folks.

 I put the rifle up untill I get more time to tear into it. Luckilly it's not my only gun.

 I have used those JSB lights and had good results in other rifles. I worried they might be a tad light for the powerfull 36  but am leaning more toward "Light" .22's.  They are flat shooting and seem easy on the mainspring...

 ZVP

I know most guys say not to do this with synthetic seals, but it does seem to work on Diana-made guns. As you know, some of the rifles power is derived from the ignition of tiny amounts of fuel in the chamber. It is possible that the gun is running on empty after extended use, and is firing erratically as a result. Put one drop of chamber oil into the port and let it sit a while, then try it and see what happens.

 Thanks again guys!

 I'm going to check ALL those points and re-do tests to determine where the problem exhists. Heck maybe with a few weeks away from the rifle I just might discover it's me... Ya never know, sometimes you make a mistake keeping a consistant hold with a powerfull, heavy recoiling rifle like this.

 I'm not going to skip anything because first of all I need to build another Mainspring Compressor and secondly, I have doubts about my own shooting. I did try several different rifles after deciding that I was actually experiencing troubles and did pretty well with those lower powered (MUCH lighter recoiling) rifles but just maybe it was me?

 AH, the "'Ol Crosman Point Trick"! Yea I really like those pellets. My .22 Stingray does too. In fact I qlmost swear they work best in that airgun!

 One advantage in doing a teardown, you can "smooth" and de-burr  the gun correctly. 

 I really appreciate the advice, thanks again!

 ZVP

 

How much vertical stringing are we taling about???? for me and my shooting abilities, velocity variation would not account for vertical stringing - unless the velocity variations are huge!!! Run it through chairgun. If you are shooting at great distances velocity vars may be a factor. i'd look for some other issue...

Just my 0.02 from a noob. I must say, however, at short ranges, the velocity variation is probably not measurable for most shooters.....

Thanks for your intrest and help!

 I was experiencing up to 3" at 50 yds. up to 2" at 30 pretty frequently. Given shooter error. I should've had near equal side to side wobbles but didn't.

 

 I put her away for a while and will re-try it all in a couple weeks. I'm gonna act like a fresh start before panicing and tearing her down.Hey it just might be me but I DID try 2 other scopes, the Irons, and several different pellets with the same results. Not looking so promising at the moment...

 These big, recioling, Magnums can get "touchy" about hold consistancy so it's always best to check yourself before deciding it's the gun.

 ZVP

 

 

These big, recioling, Magnums can get "touchy" about hold consistancy so it's always best to check yourself before deciding it's the gun...

I'm familiar/learning about this myself. Also dealt with a host of scope mounting issues. Its been difficult to discern the two b/c 1) the guns truely can be touchy and shots can go way off as a result, and 2) when something works loose/breaks it appears to be that your form has gone the SH*T (shot - in code).