Little known is that the gun that Hal Holbrook used in Magnum Force is actually a 2/3 sized replica which accounts for the size discrepancies. In real life Hall Holbrook was only 4' 1" tall. He worked around his diminuitive size and has had a quite successful career despite his stature. The car scene in Magnum Force with Clint required them to create a 2/3 sized car seat so tiny Hal wouldn't look out of place. In scenes with both Clint and Hal in frame they used forced perspective to compensate for Hal's size. The day that they shot that car scene the costume folks mislaid Hal's suit so they had to run out to a local department store and grab a suit from the husky boys suit department and make a few quick alterations.
Okay, all right, none of that is true, and by my recollection Hal Holbrook is actually rather tall from when I saw him onstage doing Mark Twain. He's a darn good actor, and still alive BTW. But, now I'm going to have to go back and watch Magnum Force for the billionth time just to see what that dang gun is :banghead: