Thanks for the link lesson.  When I first started shooting my m4-2000 I kind of equated it to shooting a flintlock...powder actually had me flinching.  With the blast shield, I actually found myself forgetting to put on my Oakleys.  (I know, eye protection...eye protection).  If the gas buster helps, adding a blast-guard should help even more.  It also seems to keep the particles away from the eyepiece of my scope.  


    I still wear earplugs with my m4-2000, and I'll still wear eye protection, but every little thing I can do to make the shooting experience more enjoyable is worth it.  Especially when it's so cheap.