"is your concern that the hammer can rotate and therefore possibly strike at a different part of the face ....which may be un square and give un equal hits ?"
Every now and again I get a wierd miss on a target , could be me , could be stabaliser, could be barrel , could be bad pellet, could be a million and one things .
My aim is to set up my kit so only pilot error can be the issue , if your confident in your kit you shoot better , it's that simple.
My rifle does about 8/10 fps over 10 shots so pretty standard for a Steyr , but i think it could be better.
I appreciate what you are saying about squaring the face of the hammer , that's something that is easily sorted.
The flimsy fireing valve itself is a slightly harder problem to solve , maybe some sort of guide for that also.
"cocking roller rubbing the hammer stem "
I watched your link and that is exactly the damage I was getting , I've polished the screw head but not marked with ink to check if it's still happening.
The hammer design for me is not great, all those thick thin sections is asking for trouble in my opinion. So I prefer the spade design if I'm honest but know that also brings issues , hence the hybrid idea.
I think if the good bits of each could be coupled a far more consistent strike could be achieved, resulting in more kit confidence.
The dark nights will be with us soon enough so plenty of fiddle time me thinks.