I got my B9 after and exchange, as soon as I unpacked it I fire a few rounds. I loved the multi scale pistol scope, I put it on my sons 2004 and installed a red dot on the B9
.
The B9 was crap
, but I expected that. I took it a part, all the edges are sharp so I cleaned that up and removed all that awful gunk. I know the US model is rated at 700fps but actualy barely make the 500fps. Mine settled down at 380-400fps 
.
The piston is undescribably poor workmanship
, dents and cracks, I refaced it as it was crooked and removed about 1cm.
I had to make a new seal screw as the original was crooked and did not screw all the way in. The seal is leather and tried to change it for teflon but I could not get a good seal.
The piston cylinder was and still is the worse of all
. It is extremely rough, has not been smoothed out after machining. I sanded it and polished it as best that I could but it requires to be re-bored with a piston cylinder boring tool of some sort (brake cylinder borer as suggested by Scruffy) the surface is still uneven but much smoother. I added two washers in the piston and re-lubed everything with Jig-a-loo.
The magazine is, so far, also crap
, I load one by one and blocked the mag hole so pellets dont fall it it.
The barrel, like many other B9 has some rotational play
, about 2mm, caused by an inaccurate breach to barrel fitting. If I tighten the nob reaaaaal good then it stops, I have yet to find a cure for this.
I added some glazed leather on the piston/spring metal housing, this way it a bit warmer when I rest my cheek on it.
Now it is real smooth, shoots crosman premier between 485-495fps. It is very accurate and not so hold sensitive.
Edit: as for the trigger there is not much to do. One can remove the trigger or sear spring to make it lighter, but this is also a safety feature, should one of the two springs fails the sear will still engaged. I cut down the sear spring by 3 coils this has made it a bit lighter.
