Originally Posted by mike
Keep us updated on your progress, intrested in how it ends up.
Well, after an extremely long blown out affair I finally seem to be getting somewhere. I've eventually replaced the reg with a new one which I basically just covered the carriage cost for. In theory Walther/Hammerli will service your regulator if you send it to them. In practise what actually happens is you send you old reg in and they supply you with a new one in return. I'm pretty confident that wasn't my problem but I could see that a previous owner had messed with it (poorly I guess judging by the marks) and I wasn't particularly happy about that, so a new reg for about 20 quid wasn't a hardship.
I narrowed down my problem to the firing spring. On inspection it had a slight kink in it and that was affecting the hammer action. After experimenting with various washers of ridiculous minute difference I finally got the power up again without the valve been stuck open releasing air. (this is NOT an illegal power up thread btw)
With the difference between the washers I choose been so precise I realised a kink in the firing spring could be a big problem. After ordering a replacement spring and probe o ring from Judith who was recommended on here and I'll have to search who gave me her details, I'm hopefully nearly done. Replaced these to much awkwardness and took it to the range. The idea was to fire a load of pellets through to let the spring and reg settle in as it were. Even just today the improvement was vast. I zero at 27 and resting on a bench I achieved at worst 5p size groups. Forgot my chrono but before I left the house it was 11:4ft/lb which is where I want it. The big concern is whether there is much spread in the string which after today I'm confident there isn't. If this nice still weather goes into tomorrow I'll be back to Bob Dunkleys range to confirm.
Sorry for the long waffle