So this morning I took the pump arms out of my 107 and 108.
The 108 arm was about half a cm shorter.
I adjusted the 107 arm to be exactly the same length.
But the 107 forearm still drops down when there's no air in the valve
![Old Confused](images/smilies/confused.gif)
And the forearm opens up again when I pump the cocked rifle and then open the arm up a little. So there's still a bubble of air in front of the pump cup, which should have gone into the valve.
Perhaps the 107 has a different position of the valve wall in de tube?
As in, further towards the rear of the rifle, so that I actually need to make the pump arm quite a bit longer than the 108 one?
From the outside the actions look identical.
Hmmm.
Will have to do more testing - hopefully tomorrow
![Smilie](images/smilies/smile.png)