Brocock concept standard 6s .22

Hello all , new member but long time lurker and was wondering on some info. Cant find much info on the brocock concept s6 standard there is some but im needing help with accuracy.

With every pellet ive shot it will stack 5 out of 6 shots the random 6th is always a flyer does not matter gr or brand 40yrds and under one tinny hole except flyer but when i go over 50 to 55 yd the group will open way up. 

Not sure whats going on as ive read these are supposed to to be very accurate and i enjoy this guy. Also im using a donny fl emperor.



Thanks in advance 

Mod edit: moved to PCP Airguns forum
 
I had a Concept S6 Standard. Very accurate with H&N Barracudas. When i 1st bought it, it didn't shoot as well and i had problems with the magazine indexing. I removed the moderator and the groups shrunk considerably, however it was LOUD! I changed moderators to a Neil Clague and that helped a lot. Then i disassembled the magazine indexing mechanism on the rifle and cleaned it up. After reassembling it, it was a different rifle. Haven't had a single problem with my Contour S6.
 
well I though I would post an up date. I found a way to load this gun single shot not practical in the field so I may try to make a single shot tray in the future. Anyhow I shot 2 shot strings 1 at 35yd 2nd at 55yd. the 35yd group most touched with 2 in same hole. at 55yd they were almost touching could do better but cant hold it steady. my point of impact chanded almost 2 inches at 35yd not sure why maybe the skirt being un alterd