From memory pretty easy. I had the seals from Robb and if I recall correctly I just took off the leather heads and used the central screw to thread the new one on. Its threaded into the piston rather than a threaded projecting rod.

I've done at least two of mine from memory (cant be sure as I have 4). Its my personal experience it has been beneficial but that is not everyone's experience going by a thread not so long ago.

Nice rifles. I especially lusted after the WBPS Marauder version back in the day.

Dave