There are 20 masses being accelerated along the length of the pipe. The reaction to this is what accelerates the pipe.

Yes , the rail gun is accelerating 20 masses at any given time, and as a result of the force applied to accelerate the 20 masses in one direction , the pipe is accelerating in the opposite direction.
and accelerating 20 masses requires 20 forces.
and these 20 forces cause the pipe to accelerate in the opposite direction according to newtons laws of motion.


At the same time 20 other masses are free-floating in the opposite direction.

Yes, because these 20 masses are not being accelerated
they will not counter the acceleration of the 20 masses occuring in the
rail gun.

according to newtons laws of motion.


Both sets of masses reach their ends at the same time, where they're both turned around by a 180deg curved track/etc. The reactions from these two turn-arounds cancel each other out.

Since the masses being accelerated will be traveling slightly faster than the masses that are floating the other way , there will be a slight difference in the timming that the individual masses reach the 180 degree turnarounds.

the individual masses that are being accelerated in the rail gun will reach the turnaround slightly faster than the individual masses that are floating to the other turnaround.


Repeat indefinately.

Yes , or as long as you need to accelerate the pipe.

so you have a continous force in a single direction
that applies to the pipe causing the pipe to continously accelerate.

according to newtons laws of motion all the above is well within his constraints.

this could be used in a space ship for propulsion.
as long as you have a ample power supply to power the rail guns.
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.