Apologies for not reading your question more carefully earlier - the pics give a much better idea of what you're comparing
One thing I'd point out, not covered by Turiasas, is that on the weapon compare tool, you've set your Professions for both Hit and Damage to 100.
On the weapons chart, you don't.
It doesn't make a difference in this specific example, as no data has been recorded for the level at which hit ability is maxed - but it can do, particularly when looking at unmaxed weapons with SIB.
So, the comparison is:
Weapon compare tool: 2.89dpp
Weapons chart: 2.959dpp
2.89 * 102.38% = 2.959
The 102.38% is the effective markup: (weapon decay * markup + amp decay * markup + ammo * markup)/(TT weapon decay + TT amp decay + TT ammo).
As the amp is non-L, and the ammo has no markup, the 129% on the weapon decay is the only component with markup.
Note that this 129% is a stored field on the weapons chart which was entered in Jan2013, whereas the weapons compare tool lets you easily personalise that so you can see the calculations based on the actual auction price right now.
I use the weapons chart as a quick sort and filter listing. But I make individual comparisons based on current pricing using the weapons compare tool.
