There was a time when I would not have believed that we would see the day of having to specify 'metal guns'.
I don't like the way the plastic ones feel, so I ordered a metal gun (CZ SP-01) as my first gun, lol. Guess theres a bit more maintenance, but it just feels much nicer.
I use a Lubriplate product that NGLI #0, very soft grease and works great.