I've found that Puma pairs do very well in this regard, as long as they can focus fire on one part of the armor (i.e. front armor, turret, etc.) They have MASC and GECM, as well as low profiles, making passive runs almost undetectable if they hug the edge of the map. While fairly expensive, every variant but the A can do this pretty well, and because of their speed, they can get back out again.
A starter Mech that can do this fairly well is the Uller A, as the CGauss does excellent damage. It's basically a suicide run though, as the Ullers can't really stand up to anything else at the point where people can even afford long toms, and you can be sure the long tom driver is bawling out at the top of his lungs for help.