Been doing a bit of `online searching ` and i found an interesting read in this post by Simon Howarth ( Tench or Tweaky )
The std ultra is made in many versions, the later ones with the number 2 on the breech use the scorpion hammer assembly, this is a heavier hammer than the earlier versions which achieves the required force at the firing valve with less spring preload resulting in lighter cocking effort but a slower hammer action, the hammer travel is around 18mm, i have modified my own target rifle to a hammer stroke of just 5mm, this gives a very fast lock time, but it is a bit more i