I'd like to see some of the specialty ammos made available and for vehicles/mechs to be able to manage their ammo from the ammo buy screen (perhaps make that available by default when you are out of base, just disable the buy ammo portion).
Specialty Ammunition I think may be add to the game:
AutoCannons: These are based on special munitions from CBT (though they may have different names). Standard AC only.
-Flack Rounds: spreads out sort of like LB-X rounds. Makes it easier to hit aircraft and infantry, which they do standard damage to (although it is done with splash damage). Very low damage against hard targets like vehicles and 'Mechs. Fewer rounds/ton, same damage.
-ER Rounds: Increases range by using a lighter shell and more propellant. Slightly lower damage. Same rounds/ton. Round has higher muzzle velocity.
-Armor Piercing Rounds: Higher damage against hard targets, lower range. Less damage against AeroSpace and VTOL (over-penetrates). Fewer rounds/ton.
-Caseless Rounds: Carries more rounds/ton. Generates more heat when fired and/or causes weapon to overheat faster (or at all as the case may be).
Missiles:
Inferno SRM's: Don't deal much damage, but each missile that strikes the target causes heat to spike up. Cannot gain lock or track TAG/NARC, but can be guided by the reticule.
Incendiary LRM's: Same as Inferno SRM's. Can maybe lock on? Cannot track TAG/NARC, but can be guided by the reticule.
AX SRM's: Acid warheads. Rather than exploding they dump acid on the vehicle. Deals damage over time. More effective against Ferro-Fibrous armor, deals half the damage of standard SRM's against standard armor. Shorter range, cannot gain lock or track TAG/NARC, but can be guided by the reticule.
Guided SRM/LRM: Fewer rounds/ton these missiles would track in on NARC and TAG more nimbly.
Thunder LRMs: Deploys a mine field where the LRM's land. Triggered by Seismic sensor, so light enough 'Mechs/vehicles and hover craft won't set them off.
(these next two are technically iNARC and may cause problems)
NARC ECM Pod: Negates the benefits of Artemis, BAP, and C3 systems while the pod is active.
NARC Nemesis Pod: A unit with this on will attract units missiles fired from FRIENDLY units.
Artillery:
FASCAM Rounds: Basically the same thing as Thunder LRM's, but create a denser or larger mine field.
Obviously these non-standard ammos would have different costs.
Seriously doubt all these would make their way in, and believe that some of them may not really be feasible. It just seemed like a new mechanic that could be kind of fun, especially if there was a noticeable graphic difference between the different ammo types when fired (probably easier with the missiles).