Tophat/Spring guide fitting in Gamo CFX

[AmBraCol]

Hey guys, my Gamo CFX dumped me in the middle of a Field Target competition recently.  It's been my "go to" rifle since 2008 so I guess the old girl's due for some tender loving care and overhaul.  I started a thread in the Spanish forum with questions as to springs, etc. http://www.gatewaytoairguns.org/GTA/index.php?topic=73626.0

But my question here has to do with the spring guide and top hat in this rifle.  It appears to me that there is about 0.300 to 0.400 of space between the end of the top hat and the end of the spring guide when the rifle is cocked.  If one were to have a new top hat machined (unfortunately don't have tools available to do it myself) would it be OK to have it made a smidge longer than factory in order to give it a bit more weight? Also, it appears to be severely undersized (0.490 OD diameter as compared to 0.525" ID diameter of the spring) so making it to fit the spring as well as fit the inside of the piston more closely would also gain a bit of weight as well.  Alternatively I was thinking of fitting a couple of washers (or disks) in front of the top hat to create a type of thrust bearing as well as to gain weight in the piston as well.

The spring guide is also undersized, running around 0.485" or so (not quite round) OD.  It's dark so I'm not seeing too good by the light of the chinese econo-bulbs, but it looks like this is press fit into the end plug.  Do any of you know if this is so?  Should I be able to have a new spring guide turned to replace this unit and then simply press it into the end plug?

I see a lot of PCP discussion in this area but not much on springers.  I'm hoping someone here can help me figure this out.  Thanks for listening.