Modifying piston legality?

[Zyik]

Is it legal to grind off the threads on the shaft of a pneumatics piston?

[Squirrel Lord]

<R92> Pneumatic components supplied in the Kit Of Parts (compressor, regulators, pressure
switches, cylinders, valves, fittings, tubing, etc.) can not be modified except as follows:
 The tubing may be cut.
 The wiring for the valves and pressure switch may be modified as necessary to interface
with the control system.
 Mounting and connecting pneumatics components using the pre-existing threads, mounting
brackets, etc., is not considered a modification of the components. Removing the pin from
the rear of an air cylinder is allowed as long as the cylinder itself is not modified.
Do not, for example, file, machine, or abrasively remove any part of an air cylinder. Consider
pneumatic components sacred. They must remain in “out of the shipping box” condition.

So no...