Quote Originally Posted by Benelli B76 View Post
Louis, is the seal too tight a fit in the cylinder ? Also is it a thin lipped parachute seal design ? Regarding the hard cocking I have found a strange phenomena on a lot of old MK 111 rifles that the cocking lever is very tight in its hinge bracket, giving a lot of resistance. Disconnect it from the piston and see if it swivels easily. I have had to shave off some metal to make them move smoothly.

Baz
Thank you Baz. The seal isn't too tight. It feels good, when moving the piston up and down in a partly assembled state (without the spring).

But still, I wonder if it's too loose. The Webley cylinder probably isn't exactly 28 mm, as it will have an imperial size? Last time I measured I read 28 mm, but I'm not sure how precise I was.

Here's a photo of the top of the seal (a bit blurry sorry). It's pretty tough material. I'll order a 29 mm Lightning SE seal and see if that is any better. But I think I should try 5.6 mm pellets first (if I can find them...).

Yes the cocking lever is tight in its hinge bracket. But certainly not that tight that it would explain the huge cocking effort. I think that's down to the new spring, and 2 steel washers that I put on both sides of the folded top of the steel piston sleeve if that makes sense. But mostly the short cocking lever.