Regarding Batfink's 52... it was a little rough when she found it so I stripped it down and resprung/resealed it. I had heard people say the '12 ftlb' version was not good unless 'professionally' short-stroked. Maybe ... all I can say is that Batfink's is a great gun after a 'smooth out' and re-lube even though it needed some shortening of the standard spring to bring it down to an acceptable level.
The engineering quality on these rifles is excellent.
Cheers, Phil