Damage calculation ( help newbie )

[GIVEMEFREE]

Damage calculation ( help newbie )

Hello.
I have lvl50 barb with concentrate as main skill. Now I'm wondering why my damage is much lower than it should be. Without concentrate damage is
59 - 398
And the skill description of concentrate promises impressive +375% to damage,
but in reality it doesn't add that much. Damage with the skill is
138 - 575
I thought that +375% means that you multiply the damage by 4.75. That would have made my damage rock. I know it can't be that my weapon's base damage is low, because I've tested this with normal ( white ) weapons and got similar results. Can someone please explain this to me. Even short answer would be nice.
I don't know if I'm supposed to survive solo in nightmare at this level and with newbie eq. ( Sigon's shield is nice though ).Now I'm doing nm quest1 and drinking health potions frequently.

 

[F1R3STR1D3R]

The base damage on your weapon is 59 - 398? Or is that with a normal attack?
If its modified by strength, jewels, and mastery already you don't get the direct multiply by concentrate %.
This is the formula for damage:
http://strategy.diabloii.net/news.php?id=551#Weapon Damage

 

[sangfagel]

but in reality it doesn't add that much...

Do you refer to LCS (lying character screen)? If "yes" - it´s not "reality". You will do best making maths yourself, using formulae from F1R3STR1D3R´s link.

You can even check http://www.cs.colostate.edu/~deykea/d2weapons.html or this one