Lubrication is generally not needed. I would advise that if the gun is running properly not to disassemble and/or lubricate. You do need to clean the barrel occasionally.
Regarding .25 cal: I had trouble getting good accuracy with stock barrel with .25 cal K1 (as mentioned also in the video). Similar problem than with the .22 version, standard LW barrels are quite sensitive to higher velocity with pellets and combine this with K1 shooting out of the barrel, the results are unstable pellet and also slugs from time to time.
This is why I replaced the barrel with LW poly uncooked. Not the gun shoot excellent with pellets and also much better with my slugs (MP molds) but still not perfect.
I am actually going to redesign the .25 slug (maybe also the .22) for K1 to optimize the accuracy with it, despite the fact that I got several feedback that the current slug is very accurate with their gun.
All the older version of the molds will still be available.
Let me know if you need my help regarding anything.