A while back, I posted this:

http://www.ar15.com/forums/t_6_54/455836_Gamo_Whisper_Wandering_Zero_Problem_.html

TL;DR: Gamo Whisper with a wandering zero.  Would group 2-3 shots, then POI would shift and it would group 2-3 shots in a different place.  Lather, rinse, repeat.

One possible remedy I found was to clean the barrel.  So, I did. And finally, this past weekend, I had a chance to get out and shoot it.

I have to say, there was much improvement. It is still not where I want it to be, but instead of the groups shifting, they are largely in one group about 2"@25 with an occasional anomalous shot about 1-2" away from the rest of the group. But, it is now actually shootable and I think if I clean it again, maybe the groups will tighten up even more. I even hit a 1 foot square steel target at 100 yards several times with it just for giggles.

If I can get this thing making even 1" groups at 25 yards, I'll be happy.  Funny thing is, I originally got this thing back during the post Sandy Hook crisis as something I could shoot that was cheap and had readily available ammo, but I can see that even if .22 isn't hard to find, that shooting airguns still has an appeal of its own.

What method did you use to clean?

I was just told that I had to shoot 200 pellets before I could expect the accuracy to settle down.  Domnt know if this is BS, I did give up before I shot it that much.

With a new gun this is pretty true...it takes a while for everything to set.....some things take longer, the only way to really know is shooting over a chrony....and you see the numbers start to look normal.

It is a common myth that you don't have to clean an air rifle....BS....pellets are dirty, you do need to clean the barrel.  No brushes, just a patch with whatever you like...you will be shocked at the goonk that comes out of them.

Are you using one type of pellet for testing accuracy ? I'm kinda happy that I picked up a .20 cal because there are only 7 types of currently made pellets compared to the 100's in .177 and .22 I find that heavier domed pellets to be accurate and don't use the Gamo alloy pellets for accuracy or hunting as they just have a mind of their own