One thing you are overlooking is that the damage dealt by ammo powers is based off of the base weapon damage, not the total weapon damage.
So if you want to compare Heavy Warp Ammo (+50% to health/armor/barrier) to Tungsten (+70% to armor/health):
Now let's say you have an assault rifle with the following characteristics:
- 10 damage per bullet
- 25% more damage to armor/shields/barriers (a 1.25 damage multiplier)
- 2 damage upgrades (+20% damage, or +2 damage)
- +20% damage from passive and armor (+2 damage)
- The piercing upgrade that deals 25% more damage to armor/shields/barriers. This increases the multiplier from 1.25 to 1.5.
Since the weapon deals 10 damage per bullet, Heavy Warp will deal 5 damage and Tungsten will deal 7 damage.
Against health, the weapon will deal (10 + 2 + 2) damage, or 14 damage.
So with Warp Ammo, you will deal a total of 19 damage.
With Tungsten Ammo, you will deal a total of 21 damage.
Now if you are shooting armor, then the weapon will deal (10 + 2 + 2) x 1.5 damage, or
= 14 x 1.5
= 21 damage
With Warp Ammo you will deal a total of 26 total damage.
With Tungsten Ammo you will deal a total of 28 total damage.
Supposedly Ammo Powers get distance modifiers like weapons do, so the percentage of damage stays the same.
Headshots grant extra weapon damage (+50% damage to +100% damage depending on weapons and research upgrades) which ammo powers do not get.
As for damage versus lifted enemies:
- weapons gain +100% damage to lifted enemies (I think that is off weapon base damage and it is additive)
- Warp Ammo deals extra damage to lifted enemies as well, 2x listed damage in rank. So if Heavy Warp Ammo deals +50% damage to health/armor/barriers, then it will deal +100% damage to lifted enemies.
So against lifted enemies, the example assault rifle stats used above will deal (10 + 2 + 2 + 10) damage, or 24 damage to the lifted enemy. Warp Ammo will deal an additional +10 damage for total 34 damage.
With Tungsten in the same scenario it will deal 31 total damage.
This is why ammo powers are at their best early game with no upgrades, but are increasingly less useful as you gain upgrades.
Most assault rifles deal something like 10-20 base damage. Vindicator deals something like 30-40 base damage. Mattock deals something like 50-60 base damage.
SMGs deal something like 15-25 base damage.
Widow deals something like 300 damage?
I had a link to a weapon damage stat sheet at one point, but the link no longer works; the guide must have been taken down or something.