Just had a crazy though, don't know if it would be possible. Could you create an external bracket that could make the LPC a pump action rifle? What I'm thinking of would look kludgy, but might work. You attach a length of paired rails via mlok to the bottom of the handguard. Riding along those rails would ride a half handguard length section of mlok. I envision it working something like the slide drawer rails in a desk, perhaps even using ball bearings in the same manner. You would attach a foregrip or handstop to the front of the the mlok "railcar". To the back of the "railcar" you would attach a bracket. From the front of rifle, the bracket would be u-shaped. From the sides, the "arms" of the U-bracket would either be angled straight towards the charging handle holes, or form an L-shape, with the arm running to straight below the charging handle hole, and then going straight up. You could then use a longer bolt to go through a hole in the bracket to the charging handle. The other side of the bracket would connect to another copy of the charging handle on the other side.
Although it wouldn't be as clean looking as a dedicated pump action rifle, the advantage of my idea is you could take it off if you wanted to shoot prone or from a tripod.
Am I crazy, or would the above be possible?