For o-like style modules, it depend from the position of the front lens holder.
All the external tubes are the same, but the position of the lens holder change in accord with the inside optic.
Just as example, in their 5mW and 130/150mw modules, this tube can be filed only for approximatively 4mm, in the 50mW ones it can be filed away for at least 10mm, i don't know the 170/200mw rated ones, cause i don't have one at hand (yet

) ..... anyway, basically, you can file away all the "unused" part of the threaded tube in front of the module (also if is better that you left at least half millimeter, just for protection)
Is different for other types of modules, where you have the front lens right at the end of the tube, for them you can't file away nothing.
Anyway, maximum attention and care, doing this, for not scratch the lens, also if is in glass, is not indestructible (using wheel grinders or similar, can be damaged, and also the excess of heath produced from these machines can cause damage) ..... a solution can be:
Measure the space (inside) that you can file away.
Cut with a little hand-saw this space
minus 2 or 3 millimeters.
Refine it working with hand tools (and care

).