Food for thought for those finding their Gong mast a bit soft with their L or XL wing, here is a way to get a more rigid feel (it is not mine).
Gong mast: 109.5 x 14.7mm
Axis mast: 119.1 x 18.9mm
Pict 3: once your fuse has been milled by 9.5mm in length and 2 x 2.1mm in width, you cannot go back anymore.
[Credit to Dave K]: You have to adjust the new mast position slightly to avoid conflicting overlap with the existing M6 bolt tap locations in the fuselage. I had the machinist line up the forward Axis M8 bolt location to the existing forward M6 bolt tap in the fuselage. It moves the new mast about 1cm forward of the current mast location. No biggie, and it works great.