Hi Ian. Yes I have been reading your thread with interest.
Late this afternoon I received a call from Jeff. He had gone ahead and fitted a new comparable spring that I had left there; I think it is a Meteor from a bunch of springs I bought off Richard way back.
Compared to the readings with the original spring (mean 600fps), the readings with the replacement spring gave 674.1 - 655.5 - 634.1 - 646.5 - 655.2
A change to a fresh breech seal saw 677.3 - 672.0 - 676.4 - 667.6 - 677.8
5 pellets shot over the garage range of 7+(?) meters= 3 holes in the target
These figures are using H&N Excite pellets. I am happy with those results; wouldn't anyone?