Rifleman RFL-3C

Description
The Rifleman's 3C variant packs a heavier per-shot punch while also improving the survival of the ‘Mech by adding extra armor and helping its heat problems. The downside is that it's heavier Autocannons force it to come somewhat closer to danger, making positioning and support from better armored units critical.

Loadout
Two UAC/5 with 4 AC/5 ammo, one heat sink D and no jump jets will net you 180 total damage and still be heat neutral while still at near max armor. Your max range would be 540m which is quite decent.

For extreme range, three UAC/2, three AC/2 ammo, a TTS +3 accuracy ballistic, no heat sinks and no jump jets you can deliver 150 total damage at a max range of 720m, but probably more with the -2 range penalty. You'll be an extreme long range sniper.

Strategy
The Rifleman has a Rangefinder Suite that gives -2 recoil and range penalty and +100m view range. Using autocannons is probably best, especially mid to long range weapons because AC/20 will make you move in close to enemies and the Rifleman is not a good damage absorber. You get structural damage quickly and need to repair causing downtime. The mid to long range weaponry will ensure your Rifleman stays safe and sound.