Weapons Special Abilities and Damage

[Sinclair]

Hello!
I am quite new to Alpha Strike and was reading the rules in advance to my first play. Now, I have a doubt about Weapon Special Abilities (like AC, LRM, SRM...) and Damage. On the Special Abilities, the rules seem to imply that you either use your conventional Damage Values or the Special Ability, like AC, and not both in conjunction. Those Special Ability Values tend to be quite lower than conventional attacks, so it makes sens to use them only when you want to use an alternate munition... however, the rule for Precision Munitions (p. 145, AS:CE) really confused me:
"If a unit using precision ammunition chooses to attack with only its AC special ability, it applies a -2 Target Number modifier to the attack instead of receiving the damage bonus indicated above."
Now, that "if a unit... chooses to attack with only its AC special ability" looks like units migh have a choice of actually using their special ability in conjunction with other kinds of attack... can someone please tell me what am I missing here?
Thank you!

[nckestrel]

You have two choices while using alternate munitions (with AC, SRM or LRM).
1. Make a standard weapon attack. This uses the standard S, M or L range damage values on the unit but is noted as using the alternate munition.
2. Make a special weapon attack. This uses the special ability damage (from AC, SRM or LRM) only and uses the alternate munition.

Many of the alternate munitions have different effects depending on this choice.  Or some require one or the other.
Swarm LRMs, for example, start as a standard weapon attack, but if you miss, then make a special weapon attack on a nearby unit.
Precision ACs, you choose to make a standard or special weapon attack.  If standard, you do the standard S, M or L damage, +1 for the precison ammo. If special, you only use the AC's S, M, or L damage, but you are more likely to hit.

[Sinclair]

Ok, let's see if I got it.
Essentially, the values I see after the Special Weapon Ability are already integrated inside the standard attack value.
That is, in a HBK-4G I have 4/3/0 and AC 2/2/0, so at Short Range I have 4 Damage, of which 2 are given by the AC.
This means that when I attack with that Mech I have the following choices to make:

1) Do I attack with standard values (which include the AC) or with the AC special values only?
1A) Standard: I use 4/3/0
1B) AC special only: I use 2/2/0

2) Do I attack with alternate munitions?
2A) No, and I get a normal attack.
2B) Yes, using precision munitions. If I use the standard attack, I get 4/3/0 with +1 damage if the target has a move of 10" or more; if I use the AC special only with precision munition I get 2/2/0 but with a -2 Target Number modifier.

Did I get it right?
Thanks!

[koraq]

That's the way I read it.