Hi Ed
I do have some Webley GP's which I haven't tried yet so I will give them a go at long range.
We now have 6 benches set up under cover on our 50 yd air rifle range at Leics & District (Dowry Hill) and we may well need another couple for the summer, as shooting spring powered rifles at 50 yds is very popular at the club
We have the full spectrum of springers between us including the AA TX's and Prosports, new Walther LGV's, HW 35's, 55's, 77's, 97's and 98's in both cals., FWB 124's as well as the older BSA's and new and older Webleys.
It is interesting that there is very little difference between the accuracy of most of the full power guns as long as a consistent hold is used and the shooter is familiar with the guns trigger pull and a bit of pellet testing has been carried out. But the .177 rifles consistently beat the corresponding .22 version by about 15mm in group size at 50 yds.
My own Mercury Mk3 isn't the only good one in the club. Another member Andy D has an early .177 Mercury with a pinned breech that is surprisingly accurate. He has just had his TX200 (.177) completely modified by Nick Murphy (of Zenith and FT fame) with major internal changes including an alloy piston with a different stroke and it will be interesting to see how this performs at long range.
A couple of our members are using springers in the UKBR22 - 50 yard Winter benchrest postal and are doing very well.
ATB
john