This is my second line intermediate support build. Think of this as more of Lance Designated Marksman rather than a Sniper: The DM's role is to supply rapid accurate fire on enemy targets at ranges up to 500 meters (550 yd) with a rifle capable of semi-automatic fire called a designated marksman rifle equipped with a telescopic sight. Like snipers, DMs are trained in quick and precise shooting, but unlike the more specialized "true" sniper, they are also attached to an infantry fireteam and intended to lay down accurate rapid fire at valuable targets as needed, thus extending the reach of the Fireteam. http://en.wikipedia.org/wiki/Designated_marksman It uses standard PPC's requiring less cooling for greater sustained fire supplemented by the 2x MLas for higher DPS.
I don't think the weapon config you have is even close to "rapid" fire, as AC2's would be considered the fastest firing rate, followed by the UAC5, AC5, LBx, AC10, Gauss, then AC20. I like the idea of 2 backup ML, but you have that Gauss too low for it to be sniping in that arm. Could you please share how group your weapons?
You seem confused on how they're using the word "Rapid". When they're talking about rapid they talking about the difference in speed between a bolt action and a semi auto rifle. An example would be how the M14 compares to the M40. The M40 on hold 5 to 10 rounds and the bolt carrier group is manipulated manually between shots to eject the spent round and chamber the next versus a semi-auto M14 that holds 20 rounds and automatically ejects the spent round and chambers the next with every pull of the trigger. What you're talking about is more like a fully automatic carbine or crew served Squad Automatic Weapon where the trigger only has to be pulled 1 time and the weapon sprays cartridges. This is not what the DM or sniper use or do 500+ meters. Anyway... we're debating 1 word cherry picked out of context . As for the Gauss rifle being in the Arm, I don't see the problem when you have JJ's. As for the weapon groups I have the PPC's on 1, the gauss on 2 and the MLas on 3 just in the off chance that a light or medium mech is in my face I can uses the Gauss and MLas without firing the PPC's at reduced damage generating excess heat until they either back off or I put 90 meters between me and them. Again though this builds role is to support from the second line. If you're being charged at and you're not with allies, things have gone horribly wrong.