What the heck is going on with my Diana?

[Methuselah]

if you changed the breech seal they take time to break in! and could take up wards of a few tins of pellets to start sealing right! and another thing I would check is how consistant are the pellets you are using? have you measured them? I'd say IMO that what you are seeing is normal for that type of rifle! it isn't a target rifle! its a break barrel and a entry level gun from Diana not that that's a bad thing but IMO I myself included sometimes expect to much from things and drive myself nut's to make something perfect that just will never be! JMO

Sorry to pull up an old thread but I like to search the site first when I have a problem.   I'm trying to fix a breech seal problem on my air hawk and came across this comment.   Should I expect my new seal to leak for a few tins before the leak goes away?   I'm currently working through additional stock shims and adding coils of dental floss without much luck and the idea that it may not seal for a while has me wondering.   thanks  john

I do that too and am investigating my breech seal fitment which seems flush. I've read it should stick out and the rifle shoots high with a scope. I've also read there should be metal to metal contact. Seems contradictory.

Anyway, people will see this thread if they do what i did, search function. Seems resolution was never stated (unless there was another thread started). Makes me wonder if a scope replacement fixed the issue (pics are gone, but not hard to imagine understanding the problem), or did the rifle get sold, yadda yadda yadda.

I thought I might just add one other possibility that came to mind. The barrel pivot. If not cocked consistently maybe the "shift" is there?

Anyway, interesting thread.

[longhunter]

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

Not necessarily. I have / had several springers that shot to the same poa, n matter if they were directly on the bag, or, supported by my hand, with no change in group size.
My RWS48 was like that, and my Diana k98 is like that. So was my xs25 / RWS 34 clone. It depends alot on the weight of the gun, and the tune/ how smoothly it shoots.

[mikeyb]

... am investigating my breech seal fitment which seems flush. I've read it should stick out and the rifle shoots high with a scope. I've also read there should be metal to metal contact. Seems contradictory.
...

Not really contradictory. An o-ring breech seal should stand a little proud of the machined breech face. Opinions vary but IMO seal should be 0.010"-0.015" above flush. When the breech is closed the o-ring is squashed until there is a metal-to-metal contact on the breech surfaces. This is a SOLID repeatable position and will provide minimal to zero air leakage (properly squashed/loaded o-ring) and optimum shot consistency.

If the o-ring is flush or below flush the breech position is still metal-to-metal solid but there is air leakage. Barrel position will be consistent but velocity will NOT be consistent and accuracy will suffer.

If the o-ring (or ANY type of breech seal) is too proud then the lockup position will depend only on the squash of the o-ring. That will VARY over time and barrel position will wander. Air leakage may be zero but the variable barrel position can cause vertical stringing (poor shot consistency) depending on how you close the barrel. Been there & done that with too fat o-rings that caused more problems than they solved.

If your rifle is shooting high a fat o-ring may seem to solve the problem of barrel rise (opposite of barrel droop). It can for a short time but it won't last.

I was still learning about springers when I posted this...
www.amazon.com/gp/customer-reviews/R3LBM8105Z0SAF
Basically a clone of your rifle in a different stock.

[Methuselah]

The contradiction I was referring to is that if what I'd seen was true about needing metal to metal contact then it would seem more oring compression shouldn't effect droop.

At least that was my thought process.

Nice referral on the link 

[mpbby]

The objective is - all the factors considered, consistency.
 
Rifle - chronograph; if FPS is 'normal' and ES is up to 4%, you should have enough consistency.
Pellet - with HN FTT and/or JSB exact you should have enough consistency
Scope - good mount, good brand, good warranty policy;  don't abuse it = keep it within the comfort zone (when zeroing, max of 1 turn from the optical center for both turrets); if needed, bend the barrel.
Shooter - find how to hold and rest (always softly); do a good trigger job (always squeeze smoothly); be repeatable

Troubleshooting - If rifle and pellet are ok, I always suspect if the scope is - still - holding zero (for this rifle).

Scope test - optical centering (mirror); about 3 or 4 shots just to have the recoils..; mirror - is the scope still centered? If not, the scope don't resist to the recoils of - this - gun; maybe it's still ok for a PCP or .22 LR.

To enlarge the scope lifespan holding zero, try a dampening mount - ZR and/or DM Sportsmatch.

If you are not competing, find what groups size are 'enough' to your needs and to each distance. This is the main shortcut to enjoy.