Valuation please, BSA Mercury Mk3 .22 Calibre

[ken69]

Just read a little further on one of the info sites, don't know how accurate it is, looks like the pin was replaced by a bolt on the 'S' model

"Differences between versions
Changes between Mks are far from straightforward as BSA would use up parts on newer rifles, they all had beech stock and the internals are similar.

Mk1 - Steel, single-stage trigger, single-piece cocking arm and a blued finish - serial number prefix WA 0.177/ZA 0.22 [1]
Mk2 - Plastic, single-stage trigger,single-piece cocking arm black painted finish - serial number prefix WB 0.177/ZB 0.22
Mk3 - Two-stage trigger, 2-piece articulated cocking arm and a blued finish - serial number prefix WC 0.177/ZC 0.22
Upgrades
In response to competition from German Manufactured Air weapons,’ it was re-launched in 1980 as the Mercury "S" with a checkered Walnut stock, thicker barrel, an articulated cocking lever, metal open sights, the barrel axis pin was replaced by a bolt and the metalwork had a blued finish.[2] The quality of the "S" version is considered superior to earlier guns - serial number prefix WH 0.177/ZH 0.22"

Also had a little read of 'The Golden Century' which states that the Mk3 was introduced with an articulated cocking lever and an alloy piston head, no mention of the barrel axis pin being replaced by a bolt on the standard rifle, just on the 'S'