There's no such thing as too much ammo for gauss rifles. ;)
I think this is the only weapon we can say this about.
It's interesting because the three vars are all very different beasts. The 9J can sink a running alpha, but does it really need to? Most of your day should be spent at 15-20 hexes out. With 65 rounds of gauss, you should be like, "12s to hit? Why not?" I'm not a huge fan of mplas, the short range eats most of the pulse buff. A regular mlas would probably get at least more chance to fire before a mplas gets into range, and ERmlas probably has 2 more chances to fire, and either one is half the mass. But they are decent for close range backstabbers trying to get in under the gauss minimum. The small laser, on a 95 ton assault? I'm guessing it's there because massaging cockpit chair and Dolby 7.1 surround sound with subwoofers only came to about .49 tons.
No doubts, it is a beast. Just keep the range open, and tape down the triggers.
The 9FC is a different animal. The LB 10's shorter range mean this Nightstar is going to be taking considerably more fire. The 9J is a lethal sniper, supporting teammates from the next town over. The 9FC
is one of those teammates. After a couple turns of attention from a 9J, you are either out of the fight or you have got daylight peaking through your armor, but as long as you keep your damaged right side away from that monster on the hill, you'll be okay. OHCRAP! The monster has a brother and it's brother has paired sandblasters and I'm stuck between them!!!!
Between slugs from paired LB 10s and the PPC, this machine is well equipped for making holes, then exploiting them with cluster, although the ammo is a bit thin for fighting other assault mechs. As the forward element in a formation that is anchored by gauss boats, those twin LB 10s are very scary to anyone with breaches. Yeah, they aren't as scary as twin LB 20s, but they do reach 50% farther with correspondingly better TH numbers.
And now for the 9SS... When your load out contains AC/20s, plural, you know will occupy a great deal of the enemy's thoughts. A running alpha strike(ultra on standard mode) will leave you with just +1 heat, and a jumping alpha will give you +2. But really, you can subtract 1 heat from those figures because, how much are you really going to use that small laser? Those mplas will be more useful since your big guns only reach 10 and 12 hexes, respectively. But if you drop two mplas and the small laser, then you can let 'er rip with that Ultra 20, LB 20 and one more mplas for fun and stay heat neutral on a run.
Unlike most AC/20 applications, the 9SS has plenty of ammo to go around. 15 rounds for each gun. That's almost 3 minutes of sustained John Woo, A-10 BRRAAAAAAP! action. But the 9SS is completely harmless to anything standing 13 hexes away. Given that its fluffed as a Solaris dueling machine, that's not as big a deficiency as it might be in a general service machine. That said, the Steiner, Marik, and Davion arenas are rather large and offer some good fire lanes. The Liao arena is huge as well but it's forests are so dense that breaking LOS shouldn't be hard, especially for a jumper like this.
Weapon placement does reveal a issues the wise pilot should consider. Two out of three mplas are leg mounted, which means they can't be fired from partial cover. Then there is the LB-20, which fills the right arm, and intrudes into the torso. Which means this monster gun's firing arc is fixed to the torso weapons arc, rather than the arm. So no torso twist, reach back and cluster spam that jumpy-backstabber in the face for you. It also means that despite a complete lack of hand and lower arm actuators, this thing can't flip its arms like a certain Rifleman was famous for doing.