The build looks solid! Only major thing would be to take the ton of MRM ammo out of the CT, it'll be vulnerable to critical hits once your CT armor is gone and if it gets crit it may explode, which will pretty much instant kill your 'mech. I'd stick it in your right torso, or your left arm if you're using the right side as a shield. It'll get used before the ammo in your legs, at which point it won't explode if it gets crit. Honestly four stacks of MRM ammo should be plenty, but see how much you end each match with and adjust as needed. Besides, the ammo skills help a lot. Remember ammo you never use is wasted tonnage (and can explode) so don't bring too much.
Other than that you could swap from an ER Med laser to a normal medium laser to save a bit on heat. Really you're probably not hitting max range MRM shots anyway, so ~300 meters is a good enough engage range.
Balancing the armor between the two arms works, but you could also put most of the armor in the right arm and use the right side to tank. You only have the AMS in there, so losing it isn't the worst thing in the world, and it keeps your left side safe for a bit longer. The build works for having a shield side, so you may as well use it.
I don't know what you have for skills, but for this kind of build the acceleration and deceleration quirks in mobility (Kinetic burst and hard brake respectively) are excellent for quick trades from behind cover.
Edit to add:
You could also swap the MRM30s for a MRM40 and 20. It'll give you the same damage per volley, but the cooldown won't be synched up. That's not necessarily a major problem if you're poking over hills anyway, and having the 40 and 20 mix generates slightly less heat and is a ton lighter. I'd consider it a good trade for the staggered cooldowns, but that's up to your preference.
The MRM40 may also fire in a slightly longer stream of missiles because the physical launcher on the 'mech doesn't have enough tubes for the full burst, which is something to keep in mind, even if it is a pretty minor thing.
As a (probably) last note, you could put Light Ferro-Fibrous armor on to free up a bit more tonnage. Could go into a bigger engine or just more armor on the arms, depending on what you do with the rest of the build.
Edited by Guardian Soul, 06 February 2021 - 03:30 PM.