Quote Originally Posted by robs5230 View Post
Sorry to see that didnt work Pete. A couple of questions...
How old was the piston seal ? They're crap at best.
What spring did you use?
What pellet did you test power with ?
How tight was the spring on the guide you had made ?

I really can't remember much about when I did mine but it made way more power than that.
Rammers work very differently to a springer. Much quicker lock time due to the higher pressure.
One of the issues is maybe the spring itself.
I'd have fitted a Titan or other stiff thick spring for sure in mine and very likely used the hw35 or 80 sized "export type" spring, as they were both springs of choice for me in the early to mid 90's. It may well have been an OX i fitted.

Another valid point may be the "oversprung " thing. When I did mine I did it alone without a spring compressor. I've never owned a spring compressor so it wouldn't have been that hard.
The piston seal was in the gun (obviously) so not sure how old it is, I did try fitting a new one but buggered up the dovetail part fixing lug because I didn't use the magic Theoben way of fitting it , I used a Titan no14 spring which I had to shorten by 3 coils as it was impossible trying to get it in the cylinder without doing myself an injury or risk having it torpedo around the shed, I used the usual .177 AA domed pellets, the spring guide is a snug fit, not tight that you have to really push it hard to get it on.

Like I said before I didn't really give it that much time as the circlip that holds the rear guide in looks a bit worn and I didn't want to risk breaking it as with most Theoben parts now they are either hard to get or bloody expensive, I could have tried some preload washers and that may have got the power up into the 10ftp area but like you say, I think the seal may need replacing but I don't really want to spend another £30 at the moment on another seal when my next project is waiting to be worked on (infact I've just bought some stuff for it today).

Pete