Weapon Group 1: 2x AC20 (Chain Fire) Weapon Group 2: 4x SMLL (Linked Fire) Front loaded armor, run it straight at things... Works well on dropping Direwolves, Timberwolves and most any Heavy/Assault mech.... Cheap but effective build. Extremely short range brawler.
http://www.mechspecs.com/forum/index.php?topic=1650.0 Similar build already exists. Also, highly disadvantaged with its non-functional speed. You're relying on enemies being close enough to get to you, which simply just doesn't bode well on certain maps where you don't have much of a choice eg. Alpine. The classic Gausscat is significantly easier to build, you can still fit in an XL (losing side torsos is a non-consequence due to its CT hitbox anyway) and you gain a significant range (and heat) advantage.
The OP build would be crap but since it does not even mount the required 10 heat-sinks it's simply not regulatory. About the "crap" part: you have 22 free slots and didn't upgraded the structure (= 3 tons lost). Not to mention 2 AC/20s with no double heat-sinks is impossible to manage.
Let me apologize.... I am unclear wtf I posted, but the build I had thought I posted was as follows... I just looked in my in game mechbay and was wondering how many beers I had when I translated it to smurfys (far too many lol) Thanks for pointing it out! OP has been corrected Additionally my apologies if this was posted before, as I see now the 4ml version.... Gauss Statement: XL and Gauss are a disaster with Clan tech ingame now. Due to the "spreading" of damage from PPC hits and such, the Gauss (not it's ammo) blows up like a bottlerocket... any torso mounted Gauss is way too volatile for my liking. Side Note: I run this as a complete support to assault mechs, thus I usually am secondary target that can close the distance while the big boys duke it out.