Modifications to a Mont Blanc Ball Pen refill for the Pilot G2 pen.
Open the Pilot G2 pen and remove the G2 refill. (Figure 2)
Remove the plastic tip protector from the Mont Blanc ball pen refill. (Figure 3)
Using a knife (or sandpaper) trim the three fins located on one end of the tip protector to be flush with the tip protector body. (Figures 4 and 5)
Now cut off a 12mm section from each end of the tip protector to yield two 12mm sections. (Figure 6)
Put the 12mm section that has an opening on both ends onto the ball pen refill. (Figure 7)
Drop the remaining 12mm section into the top barrel of the pen. (Figure 8)
Insert the Mont Blanc refill and reassemble the pen. (Figure 9 and 10)