my standard rivet gun has a multiple 'rivet size' capability which includes 4 or 5 sizes of tips for everything from super tiny rivets to large rivets, including plastic ones.

i got mine from some specialty store over 5 years ago and it works fine. its not the green one, nor the $13 one. i'd give you the model # but i'm 300+ miles from it. it has 5 tips, and works fine. adrian's solution is also a great idea.

i recommended the wrong gun as i had no problem with my 'non green not solely plastic' rivet gun. i apologize for the inconvenience.