I'm not aware of any +.080" pistons for the M20...If your barrel is good other than the liner I'd say a new liner and piston is the way to go..(bearing in mind that if you do buy another barrel you may have to do seats and valve guides as well)....Ian
Fortunately, I have found someone else in Germany who has a liner in stock. I was really lucky!
The cylinder is still very good, I will replace the liner and put in a new piston.
BG
Magnus