How do I know how much ammo my weapons have?
When I choose to attack, they just show the stats, not the munitions.
Also, I'm using a HeavyFoot Buru Buru
That's odd, it should be listed amongst your weapon stats on the top-left corner of the screen.
Other than that, you can manually check it through your inventory or field HQ menus.
Pretty sure it'd be possible to mod that into the sales list.
I've done it before with custom items, I'm sure weapon clips can be done the same way.
It's not difficult; the problem lies in that weapons have dozens of different bullet types so it's time-consuming to make a cartidge for each one. Adding something like the following to your PC_MECHA EQUIPMENT.txt file should work.
Ammo 12
Magazine 20
caliber <130mm self-propelled>
Name <L-Cannon Clip (EMP)>
Category <MEXTRA MEK_WEP>
factions <GENERAL>
Type <HAYWIRE>
Ammo determines the damage of the bullet deals.
Magazine determines the maximum size of the clip.
Caliber determines what guns can use it, examples include 45mm/70mm caseless, 30mm/120mm ferrous, Construction Bolts, 30cm explosive canister, 500mm ferrous ball, and so on. You'll need to check the weapon itself to see what caliber it uses.
Name is exactly what it says on the tin.
Category determines what type of shop the item can appear in. For mecha weapon cartridges you'd be fine with MEXTRA and MEK_WEP.
Faction determines which faction stores sell them. You'll probably be fine with GENERAL.
Type determines the bullet's special effect; a few examples are HAYWIRE, BURN, BLAST (#), BLAST (#) SMOKE, SCATTER, BRUTAL, HYPER, LINE, and OVERLOAD.
You can also edit things like Mass, Acc, and Range, possibly even things like speed and BV.