I think a weapon that almost always gets torso hits is an interesting concept, but does not really work out well.
One of the reasons that we have a randomized hit location table is because while mechs might not be moving fast enough to cause a well-aimed shot to entirely miss, they are moving around enough that a shot that was aimed at the torso might hit the arm or upper torso. Thus having an integrated targeting computer to make it so shots *always* hit the torso doesn't make sense considering game mechanics that are already in use.
Consider giving it a rule similar to a called shot: any shot that hits is transferred one location inward on the roll of a 6,7, or 8, or a 8+, or something else similar. This represents that a targeting computer can increase your chance of hitting a specific location, but cannot fully account for the movement of the target.
Secondly, I think the weapon simply has poor stats. It's heavier than a gauss rifle, does less damage, has less ammo, has less range, and has significant heat build up. While I commend you in not making a weapon that is clearly superior to existing tech, I also think that making a weapon that is clearly inferior is less than ideal. I would drop its tonnage to 10, and leave the other stats the same, including the ammo count, considering this is something of a Clan analog to an AC/10 with precision ammo.