It is not optimal and in is hard to judge from the photo
How deep it goes down the barrel, but I have a WM20 that runs great
With such a barrel.
I believe that as long as there is still enough clearance of good barrel
Above the top compression ring, (say about 2mm?)
It is usable, but it is only my opinion from experience.
Thanks for the response, the reason for changing my barrel is the damaged fins.
But I think € 30,- is not much for it, but on the other hand this outlet guide is hammered.
The exhaust valve guides are often find in this way because of overheating,
Or because not installed properly (It should sit lower than the intake guide)
It is not a big problem or expense to replace it, and with a simple tool
(Shown at the manual and easily made by lathe) you can replace it yourself.
Please note that the IN and EX guides are different length.
Whenever I install a barrel I replace them just to start from fresh state.