And if I'm honest that is where I think the AC-2 needs to go these days. That way it becomes an interesting choice.
AC-2 has a little more reach, more consistent damage, is cheaper, and if you double tap it still isn't overpowering in that dynamic.
Similarly the LRM-5 has indirect fire, slightly more versatile ammunition options, and better damage on average.
Still thinking about where the AC-5 would need to drop to in weight/crits without it being too much but still an interesting choice.
AC-10 and AC-20 by fact of the kind of concentrated damage they do are already pretty close but I'd still put both on a diet if it were up to me and to be fair I don't think you could drop much from them without it being overpowering.
Well, the AC/2 actually has a higher capital cost than the LRM-5 (75,000 vs 30,000). But sure, it'd become an interesting choice, to say the least. A Vanquisher with a 10x AC/2 pack in each arm would be hilarious. You sure couldn't implement 0 heat for the AC/2 and rid the min range at only 2 tons though, that'd be too much.
Are you thinking about other ACs or just the vanilla version? At 2 tons, the regular AC/2 would likely be a very strong competitor even against higher tech stuff, but with the upgrades on the LB-X and UAC upgrades, things can get ridiculously lopsided for the -2 if it stays at 2 tons. 2 tons also doesn't give a whole lot of room for the LAC2 and PAC2, so you need to consider what their upgrade path would be or just shoo them away entirely.
I'd hate to be the poor bloke that has to remake all the designs for every AC-toting unit though.
If you're going the weight route, the AC/10 and AC/20 do have to be lightened. At 2 tons per pop, I'd go with 5x AC/2s over an AC/10 90% of the time (and the other 10% I'd sub it with lasers + heat sinks), for the range advantage, accuracy advantage, and 5x the hits leading to 5x the chance for TACs and head hits. Concentrated damage
can be useful but it's honestly overrated, and a 10-point hit just isn't that big.
The AC/20 is scary in that it's certainly
effective with its 20-point bowling ball, but it's certainly not
efficient: A battery of medium lasers for the same weight generally ends up similar or even better while being much cheaper (to the surprise of no one). It can easily lose several tons without becoming overpowering, though not 2/3rds of its weight like you did with the AC/2.
Honestly, I think snapping off a few of the AC's crutches and giving it something extra (like FF's +2 on MoS or my modified Rapid-Fire AC idea) is a better approach than dropping weight across the board. There's less change to the designs itself so you don't have to modify them as much or at all, and you can introduce a new Autocannon line (like improved PACs or LACs) to fit the niche of "lightweight AC". But I'm a bit biased since I have a home-brew weapon concept (iPAC), and a 2-ton AC/2 would definitely step on its toes.
