This could, in my view, be implemented as either a trait, parallel to the ordinary traits for range weapons or instead of traits for range weapons.
I am thinking of stuff like; Amputator Shells, Bleeder Rounds, Dumdum Bullets, Expander Rounds, Man-stopper Bullets and so on.
The way I see it is that using special ammunition gives us more powerful shots against certain targets like how Bleeder Rounds causes bleeding damage, Dumdum Bullets makes a mess of targets without armour and so on. But in exchange we get a reduction in the ammo we can carry with us in the mission. The more powerful the shots we got, the less ammo we bring along.
The same can perhaps be done with las-weapons in that we can how powerful shots we want to use but in exchange, more powerful shots will use off the charge pack in the las-gun quicker?
With customisations so praised by the developers, I could easily see ammo types in the attachment sections. I really like this idea. Here are three examples of mine.
Rounds pierce through armour of medium thickness.
Reduced RoF (30%)
Rounds are far more likely to tear off limbs (slowing enemies down and decreasing their combat effectiveness)
Especially with bolters (hope we get at least some) there is so much more possible on top
Hellfire Rounds:
Reduced dmg vs Armor - Increased Damage and DoT (Acid) vs unarmored targets
Inferno Rounds:
Reduced direct damage - Fire DoT
Metal Storm Frag Rounds:
(More likely a Pickup then a straightup mods) AoE dmg against enemy groups
(effectivley works as shotgun - but the point of fire is directly in front of the enemy)
Oh my god I would love to see more variety in pickups instead of the plain medical and potions (+ammo refills). Imagine instead of skipping the ammo box you open it and are able to choose one of two special ammo kinds.
Now you have the ability to hold R to reload your weapon with a special magazine loaded with unique more effective and specialised rounds. If that would be the case I would also highly prefer to have special magazine counter next to the default ammo pool numbers. I absolutely hated (with passion) the special ammo mechanic in Left4Dead or that World War Z where you just get 120 rounds of special ammo all in one go and you can’t save them for later.