Replacing a Walther LGR Piston Seal

[Maverick61]

Anyone have experience of fitting a new piston seal to a walther LGR rifle ?
Have removed to old one & purchased a new seal, but cannot get the seal to deform enough to fit into the piston recess. I've tried heating it in hot water to soften it & using grease etc but nothing seems to work.
Loathed to try putting it in the freezer as I've been told they get very brittle & would most likely break very easily.

Appreciate help & advice from anyone who has managed to change theirs in the past & also to save my hands from further punnishment.
Thanks.

[18 Wheeler]

Hopefully this article from Pilkington's by Tim Johnston will help you get the job done.

Fortunately mine is working to spec, but do please update this thread with your progress as one day it'll need doing. HTH

[RobinC]

The Pilk article is on the right track, don't freeze it, get the piston scrupulously clean, use fairy liquid as lube, use an engine valve spring compression tool to press it in, wash off fairy liquid.
Have fun,
Robin

[Maverick61]

Thanks for the advice, but that hasn't worked either.
Spent 8 hours now trying to get the seal fitted to the piston & all I've managed to do is bend my valve spring compression tool & ruin the seal as it's torn the retaining ring off. Material is far too hard & will not flex to slip into the retaining ring.
My advice to anyone contemplating re sealing an LGR is DON'T, it's bl**dy near impossible & I can see why Walther recommend fitting a whole new piston & seal assy.

It's possible that the seal supplied just isn't up to the job (red in colour, walther original is blue), but I can't very well send it back now I've ruined it can I.

I'm mechanically very competent & have re sealed & re sprung numerous air rifles in the past, but this one has just about beaten me - Can anyone recommend an airgun repairer in Essex that will take on the job?

Wish I'd never seen the blessed thing in the first place now

[wonky donky]

I've used after market LGR piston seals from Knibbs & have done "O" ring conversions. Both work just fine but neither as straight forward as replacing a Feinwerbau 600 piston head.

The Knibbs item is too big in the flange area as well as in height in my experience so if you did manage to fit one the cocking lever wouldn't close even with the cam turned to its lowest setting. I have even seen experienced fully trained airgun repairers fall into this trap, the result BADLY BENT COCKING LEVERS This one was sent to me for this very reason.

When replacing the piston seal I always remove the piston from the rod & tap the end of the piston to take a grub screw, then machine a groove in the pin for the grub screw to locate.

I do this irrespective of if I'm fitting an after market seal from Knibbs, doing an "O" ring conversion or in this case MAKING MY OWN PISTON SEAL