If the rifle in question is covered by one of the bans, and/or the mags are hi-caps, advertising them in itself is *technically* illegal, under the "keep for sale" provision of the law.  Luckily, they aren't likely to enforce that, as they'd rather you get the guns/mags out of the state.  But, legally, you would have to sell these items via an FFL with the appropriate PRK AW and Hi-Cap mag licenses.  And unless this guy has letterhead from his department giving him permission to buy these items for duty use, he can't legally buy them if he resides in the PRK, even if you send them to Nevada.

-Troy