Well got my lead free .25 JSB Exact kings, 16.54gn so had a play .

Must say initial findings I'm quite impressed they're unmistakably JSB although the skirt recess is very shallow & the skirt quite thick reminiscent of accupells.
https://ibb.co/J35T9mX .

Conditions were somewhat gusty so not perfect at 40yds, the targets are 55mm, each ring is 5mm with a 10mm bull. 5 shot groups.

Now I tested them with the Rapid which has the worlds fussiest barrel & only shoots JSB/AA pellets, everything else is rubbish, and initially at full power (42ftlb) to get this;
https://ibb.co/fDJW2Fd .
That is better than any non JSB lead pellet
as a comparison, although 3 & 5 are the only ones I'm happy with
https://ibb.co/kScvYL7 .

I reckon these have real potential with the power turned down a bit, as 1054fps average is too much for a diabolo pellet, When I get a chance I'm going to fit a lighter hammer spring & try them at around 900fps.
they could be very good at sub 12.

Of course the main issue with zinc pellets remains, I dug these out of the target, lead V zinc, 40yds at 42ftlbs
https://ibb.co/VjjTD4G