hi,
link here for Benjamin bits, agree with you on the silencer adaptor, bloody ugly Going to knock up my own.
on tuning, I.ve yet to get mine fully sorted, but polishing the sears etc. seem to be recommended everywhere.
I have ground down the end of the bolt in front of the barrel seal to a taper, down to approx. 1.5mm at the point. This lets the co2 flow better, and definitely gives me more consistent grouping.
http://www.sdcustomdesign.com/parts.htm#benjamin
Russ