My rifleman stats are slightly inflated (I think my "rifleman" caps are actually my total caps as inf; for whatever reason they're not separated based on class). I don't think I do anything special as a rifleman other than playing cautiously overall. I prefer to pick a good building or group of bushes and hold a position, get a few kills, and then rotate around the terrain/town since I know that someone will eventually find me. I do have a few videos on youtube but they're either paratroop videos or with the semi-auto (which I do play similarly but it obviously allows me to get engage a little closer.
Also Xanthus, you've still got some skill because you killed me by throwing a grenade into the top floor of one of those white factory buildings the other day. Accurately tossing one of those things is something I still can't do.