Thanks M.
There's no evidence of piston slop, though it will rotate a bit but that's normal. Also, I don't know if this is normal or not as I never really looked that closely at it before, but the very last tooth on the piston rack is almost double thickness at its apex compared with the others. Seems like Systema wanted to reinforce that particular tooth over the others.
At any rate based upon your advice, I think mine's a good copy after all.
Another question: do these cylinders come pre-lubed or should I be looking at applying some myself? From the factory, the piston rack looks pretty dry to me so no telling what if any lube is inside the shell? Yes, I am a bit of a PTW noob myself.
Many thanks!
'Fly