I like miltec, if you apply it right it lasts forever and it doesn't collect dust and carbon, makes cleaning a little easier.
Edit: forever being a thousand rounds or so. Sorry for the exaggeration
Cpl Williams, Evan T. USMC, 08FEB2010 ~
D Co, 4th CEB, Engineers UP!! OEF 21JUN-20SEP2011
REV. 19:11 And I saw heaven opened, and behold a white horse; and he that sat upon him was called Faithful and True, and in righteousness he doth judge and make war.