Something doesn't add up: Steel Skin (in General)

Without Steel Skin: 412
With Steel Skin: 509

412*1.25 = 515

Anyone able to explain it?

Oh and,
Hit Points 3,057,603
Steel Skin 400,630/482,687

And if anyone thinks this is minor it's costing me 1.3 mil for each AC point. (Thats assuming I name my next two instead of using the blacksmith)

Perhaps something to do with named armor?

I took my nonnamed ones, and even they don't add up.

Without Steel Skin: 21+(9+24)=54
With Steel Skin: 66

54*1.25 = 67.5

Maybe they're separately rounded?
21*1.25=26.25 rounded to 26?
9*1.25=11.25 rounded to 11?
24*1.25=30 rounded to 30
Added up that still comes to 67.

maybe if you would post a list of all equip & stats we would have a better understanding..

An Amulet of AC [0] (+21)
Dyneema Armor [40] (+90) (Named Adam)
Steel Cloak [11] (+27) (Named SC)
Kevlar Pants [18] (+48) (Named CML)
Granite Gloves [6] (+20) (Named Tulkas)
A Helm of Durin [9] (+24)
Neutronium Shield [22] (+59) (Named MS)

With Steel Skin:
Only AoAC: 26
Only Adam:168
Only SC:49
Only CML:84
Only Gloves:34
Only HoD:40
Only MS:104

Without Steel Skin:
Only AoAC: 21
Only Adam:136
Only SC:40
Only CML:69
Only Gloves:28
Only HoD:33
Only MS:85

Any encumbrance?

Any penalties to skills tucked up in there?

Encumbrance doesn't show on the equip page. And none of the penalties should be big enough to bring my Steel skin down. Fully equipped I still have enough for 1.0 SS.

This actually makes perfect sense...

IF one only applies the naming bonus to the + value (not the base value).

I checked the numbers on lostling's +45 named CMLs...

On a char with SS and no other armour they provided 81AC

81/1.25 = 64.80
64.80 - 18 = 46.80
46.80/1.04 = 45

The information on the naming page implies this is not the case but it sure looks like it to me.

With SS:
Only HoD:40

Without SS:
Only HoD:33

33*1.25 = 41.25

Thanks for the idea, but unfortunately, that still wouldn't explain my HoD, which is unnamed. And I'm pretty sure Naming gave bonuses to the base before Steel skin.

Individual items aside,

If you take your entire armor set (item by item) and add base + enchantment (x1.04 if named),
round each number up,
multiply each by 1.25,
round (nearest whole number)
Totals 509

So your HoD notwithstanding this offers the best 'fit' of the data I have seen.

And is consistent with the armour piece of lostling's listed above.

ok... so this is strange

It appears (under further testing) that the projected AC with SS differs by exactly 1 point per item with base AC > 0

So in the original case,
Adam, Tulks, HoD, CML, MS, SC = items with base greater than 0
515 (predicted value) - 6 = 509 (actual value)

This also proved to be the case on minion I tested with EG, SB, and TSA

Weird stuff...