Vacuum pumps fitted to some flat engines can be damaged by turning the engine backwards.
I have hand-swung 172s and the like, but I prefer not to. Whereas something like a Tiger Moth or Chippy, with a long stroke engine, just needs gentle pull over compression for the prop to flick around, the typical flat engine (with the exception the little 65 horse Conti in a Cub which is a deligh to swing) needs a more sustained pull for longer and doesn't 'flick over'.
I have heard it's possible to hand-swing a Yak 52. Now that, having spent a long time simply pulling these engines through before flight, is something I would never do!
SSD