Well, Lets work through this step by step!
First off, I'm not going to be answering these questions in the order above because I have faith in your basic comprehension skills!
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Second off! Alternate ammo? It's default ammo is the alternate ammo! It says at http://www.sarna.net/wiki/LB_10-X_AC :Quote, "The LB 10-X Autocannon is essentially a 'Mech-mounted shotgun, capable of firing special "cluster rounds" that split apart after being fired. LB-X Autocannons are able to use either the special cluster rounds or standard autocannon rounds,".
This means that the LB 10-X is already using the critical hit seeking "alternate" ammo. So the only thing left for it is to implement the ammo switching during a battle. (Unless for some reason you can already do this and I don't know.)
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But why does it have a longer range than the AC-10 if it's first impression is a shotgun? The LB 10-X's name actually tells us the answer! The LB stands for "Light Barrel" or "Long Barrel" as I would prefer to call it as a longer barrel makes a weapon's accuracy better at longer range. This, however, is just speculation so don't take it too seriously.
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(Light Barrel is the spectualtion stated at Sarna.net. Long Barrel is my own spectualtion, but both would make sense.)
Next up is expense. You might think that the LB 10-X is more expensive because it's lighter than it's AC counterpart, and you'd be right, but only by half. To be more specific, the LB 10-X is a, quote; "derivative of the standard and relatively primitive Autocannon/10 design used for centuries by every military in the Inner Sphere," and that by "Taking advantage of advanced materials such as Endo Steel, the company was able to reduce the weight of the weapon for only a slight increase in bulk and mated it with the advanced Mercury-VII targeting system to boost its effective range,".
And before you start typing, there is no way that a "targeting system" could increase the range of effectiveness without the weapon itself being physically capable of longer range. Meaning the before stated speculations still make sense.
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Many thanks for reading this post! I hope this made sense and cleared the fog for those of you who didn't quite understand the LB 10-X AC! Though this all means that there is still some mechanics to be implemented before the LB 10-X AC stands above the AC 10 as it should, it's still good as a long range "pester weapon" and "weapon removing" cannon. Not to mention it appears to fly faster and straighter than it's AC counterparts.
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