I always hated the part that AMS can engage infinite missiles each turn. I think if you get rid of that rule, which makes zero sense anyway, AMS is a lot better balanced.

So if you need 234 AMS to take out 70 capital damage of missiles, well you need 468 AMS to take out 140 capital damage of missiles. The AMS needs to run into prohibitive bay penalties to block a second volley, instead of 234 being the final number needed to scythe down near limitless capital missile volleys from different directions at the same time.

Now, a more out there solution would be to make AMS act as % reducing item, with diminishing returns. If you do this, then you can keep AMS as something that engages limitless missiles in a turn, but the damage reduction never reaches 100% with a single bay. So, you would take your AMS damage (say its the 234 for 70 capital damage), and you would add your AMS damage and the missile volley damage (say its a smaller volley of 30 incoming damage). You would reduce the volley by 70 (your damage)/100 (your damage + incoming damage), so 70%, turning the 30 damage Volley into 9 damage. A 70 damage AMS would likewise reduce a full 70 damage capital missile volley by 50%, and each Kraken missile of 10 damage would get reduced by 7/8, down to 1 damage. You would need 2 AMS bays to kill a single Kraken missile, as the first AMS bay of 70 would reduce the Kraken down to 1 damage, and the second bay would further reduce this damage which would round to 0.