Walther lg55 new piston seal questions

[vbull]

The replacement piston seal I've just bought from J.Knibbs is synthetic, hard red Nylon type material that to be honest I can't see it will seal anything as it has very little give. These are apparently what's used, according to articles I've read, so I will persevere but I can't adjust the seal/cylinder fit by screwing in the dished washer, as I've been told to do, as its only just started on the threads and already is way too big therefor I need to remove quite a lot of material. I'm guessing I just spin it in the lathe using sand paper or do you think I should attempt cutting it ? Have any of you guys had success turning these seals in a lathe ? I don't want to have a go and ruin the thing at £20 a time.

[HOMER]

I have used similar seals for sometime from JM, Diana use similar material, I would guess mainly for the longievity, sizing yes they can be lathe turned but I would use @180 grit on a flat block, the trick is to get the correct angle when the seal is compressed in the cylinder (not as straight forward when its not compressed), try visualising the lips compressed a few thou +/- and aim for a reasonably flat bearing surface leading up to the face of the seal. Most importantly which ever method you use dont use a high speed, the plastic / nylon will heat and start to melt. The more material removed the quicker the seal will wear ( though we are talking many thousands of shots ), the edge may be polished (again gently and use fine wet & dry). then lube as normal with Moly GM / Rocol ASP.

Good Luck
H

[vbull]

Thanks H.