Well although the weighting and sizing improved things, it has become less and less pellet fussy as I have leaded up the barrel. I gave it a really good clean when I got it and little dirt came out, so it had probably just has two really good cleans Now its nicely leaded I'm grouping AA 4.52's and daystate 53's straight out of the tin. Much more chuffed now, thanks for all the advise, I should have listened earlier, but its all a bit of discovery. Here's some groups.
http://www.airarmsownersclub.com/vie...p?f=14&t=15403