This build looks very promising and maybe the best Brawling Build for Close Range Encounters! You still have two critslots free. I would add 1ton more AC20.Ammo and CASE for some Protection:
WHY case, you can fit all ammo at the legs, body and head. That half ton or so is better spent on armor.
For a field test, I used a STD350 (I didn't want to spend the C-Bills) which left me 2.5 tons short. This was a very good brawler. Great on River City, but will have the obvious short range flaws on a map like Alpine. I still think the D-DDC is a better all around brawler and variant. I had hopes for this variant which have since disappeared.
Well, technically an explosion in the head would kill the Pilot, which we don't care cause it is the same anyways when your mech is destroyed. Any crit in the head is going to destroy your mech, with or without ammo. And there is no pilot killed penalty, please abuse this. Same goes for having it in the CT, cause we don't have to worry about repair. If you get a crit in the CT area, it is going to do something deadly anyways, and if it is not randomized on the ammo it would be on the enging or other critical parts. Few people focus on the legs of an atlas, esp when you have good armor in them. Obviously you would WANT to have CASE if you store it in the LT/RT so explosions don't spill over. But in this case you don't have to put your ammo there, there is ample room between the CT, head and legs. The half ton of armor definitely benefits more in this case. Here