Build created for the christmas / stocking event: you need to achieve at least 250 match score, which means you need to deal around 400 damage, a single kill and/or some components destroyed. Better sustained DPS compared to the 6xSSRM4 version and more ammo for prolonged firing. Skill most of heat generation skills, get most of the armor nodes and you are good to go. A couple of nodes and a small investment (around 5 nodes) in target decay will help greatly. This is the mech I used to achieve 1000+ damage game on scouting. Spoiler: 1000+ damage ALT: remove 1 ton of ammo and fit a tag as Nanostrike suggested.
Honestly, you can get by with ~400 ammo. 500 is usually overkill for how short scouting matches are. If you shave off 1 ton of ammo, you can fit a TAG or Flamer in the nose that can really help. Tag for near-instant locks, Flamers for overheating the usually-running-hot Clan mechs.