I have been lucky with 50's so far. Currently, I have a .22 which gives all of the accuracy of a good modern springer and a .177 which is very special indeed and can trade punches with an Original 66. Bought from a 10m shooter on here, its still wearing a Diopter 60 and has been magnificently fettled by its previous owner. Im very lucky to have it.
I also have a 50T01 which is somwehat behind both but can comfortably outshoot my Mk2 Airsporter. Which isnt hard to do, admittedly.