Hi Ian, the first item 'A' looks similar to a Nikko sterling Tiara scope mount i have on my webley ranger, only in 2 pieces as opposed to my one piece which is also marked JAPAN, could be a very similar model

the rearsight in 'B' is a webley, Ranger, jaguar and junior rear sight, possibly a diana model 20, 21 and 22 too? I've been looking for one of those for an age then a week or 2 ago a guy on here sent me one but i'm still awaiting delivery

Sorry but i aint a clue what 'C' is

PAUL