Quote Originally Posted by greenwayjames View Post
The W&S Mk2 will always give poor consistent accuracy when using the diopter sight because the bolt will not return the breech end of the barrel to the same point every time. The harder the seal the better to combat this fault but over time that will cause the sights to wander off.
I've had a different experience with my Mk2 Service air rifles, which all give excellent accuracy. I was delighted to see scores of 72/75 and 73/75 when I used it for bell target some years ago. One of my Mk2s also won a vintage HFT shoot, beating others using BSAs.

John