I just took apart my Walther LG 55 and I got the following:

Bore, Stroke, Swept Volume

25, 58, 28.5

However, I also noticed in another thread somebody got a different stroke value (62-63 mm):

https://www.airgunbbs.com/showthread...ning-questions

We both got the same spring guide measurement of 30mm and the bore at 25mm.

I have the stud at the end of my piston and the Waffen Gotha In-House machined / elastomer piston seal. I'm also using their > 7.5 J export spring @ 2.8mm wire diameter, 230 mm long & 28 coils (if I counted that right).

The gun is shooting 550 fps with Superdomes .177 8.3 grain pellets.