I really like the McR-18 from McGizmo. You need to take about 1mm off the front of it though. Not a big deal, I just use a regular flat file and blow it out with a compressed gas duster afterward.
Nick, I use fine-grit sand paper to shorten the McR18. It takes longer than with a file, but you can control the amount of material you remove much easier and the finish is much cleaner, IMO.