De bur, lube tune, new piston seal and now my Octane Elite is a shotgun.

[superchikn]

After a couple of thousand pellets I thought I would do a de bur and lube tune (Krytox) on my Octane Elite.  It would group well at 30 yds usually 1/2" or so.  It is a .22.  On tear down the piston seal was ugly so I ordered an apex and a tesla seal.  Installed the Apex and my POI was a few inches low, was taking me nearly out of range on my scope so I shimmed the scope.  Seemed to still want to shoot low.  Installed the Tesla seal and shot low again, but it just wont group at all.  3-4" vertically and 2" horizontally.  Breech seal is fine.  Pivot feels the same as before.  Gas piston nothing changed.  I am shooting JSB 18s and Baracuda Hunters which were the best shooters before.  They are both acting the same.  I can try other pellets but I do not feel like that is the problem.  I am probably wrong about that though.  I dont think it is the scope which is a UTG and was fine before the tear down, would be a heck of a coincidence.  Wish i owned or had access to a chrony but i don't. 

I'll keep working on it but am open to suggestions.  This is annoying.

Thanks in advance.

[Roadworthy]

Assuming you did everything perfectly - how do the piston seals fit in the compression tube?  If they are too tight they will cause significant velocity reduction - easily 100 fps or more.  This alone could account for your low point of impact.  It should only take two to three pounds of force to move the piston and lubricated seal through the compression tube.  Of course a leaky breech seal can make for some erratic shots, too.  Are you sure your stock screws are tight - especially the rear one?  If the rear one is a little loose your barrel can droop causing low hits.  It can also allow erratic groups.  Shimming the scope is addressing a symptom.  You need to find the problem.

[superchikn]

I'm not assuming i did anything perfectly, but i just did this on my D 34 and it shoots great, (as it did before).

Piston seal is similar to factory pressure I believe.  Around 3 lbs.   No leakage at breech seal according to tissue test.

The Octane Elite is a sled type.  The entire action slides within the stock but everything is tight.

Just tried 6 other pellets in it and they all do the same thing more or less.  The only one that looks like it wants to group are AA 16s.  It normally likes heavier pellets.  I will try more light ones but I think something is wrong.  I can always throw the factory seal back in to see if that does anything.  It was pretty ugly though.

[DanD]

That sounds frustrating. 
If you grab the barrel and pull in different directions, can you detect any wiggle at the pivot or in the action?
Have you checked grouping with iron sights?
You could swap scopes with the 34 to verify the scope is not the issue.
Might be worth cleaning the barrel to see if that helps.
Good luck!