I bought a S&W 64-5 awhile back that was an Australian LEO trade in. Why isn't it import marked? It was made in the 1990s IIRC and made it's way back home around 2012.

 

The only thing I can imagine is that S&W imported it themselves and their OE markings suffice. I believe the gun came in a M&P box so they probably worked a deal with S&W.

Import marks must contain: the country of manufacture, model, caliber and importers name. If any of that is already on the pistol from manufacture is does not need to be reapplied. So as you said, if S&W imported them, they wouldn't need to mark anything on them.