Weapon Quality

I have been trying to find some guides or information on how weapon (and I guess to a lesser extent armour) quality affects the damage/accuracy figures of a weapon.

I know there is a lot of information about RW and stuff, but I am more looking at grey weapons at this stage in my torn life cycle.

I guess the main question is, if you have say a 25% quality primary weapon, and you can find an identical stat one at 50% quality - is it worth upgrading?  What is the actualy difference the quality plays, and when does it become relevant to pay attention to it?

Quality doesn't affect dmg/acc it's the other way around. Dmg/acc is generated on spawn by rng, quality is just the mathematical representation of how good it is compared to the possible attributes of that weapon.

Oh, that is fascinating - so technically speaking quality is an "ignorable" stat?  It is a down-stream calculation baased on the other stats of the weapon?

I would say it's only worth upgrading if you're not spending money. While there was once a market for high rated gray gear these days I'd advise saving and investing in RW gear when you get the chance. The difference is too big to justify spending money on high quality gray gear in my opinion.

Yes.

Not buying weapons, just want to understand the mechanic - turns out there isn't any mechanic >.>

From the wiki, I didn't know this. 

The Quality (displayed as a percentage value) that each weapon displays is essentially a combination of the weapon's Damage and Accuracy, with a score that reflects the range of its potential in each stat. 50% of the weight is assigned to Damage and 50% to Accuracy.

For example: A weapon has a Damage value range between 30.00 and 35.00, and an Accuracy value range between 50.00 and 55.00. If there is a listing for this weapon that has 32.00 Damage (a 40 percentile in the value range) and 54.50 Accuracy (a 90 percentile in the value range), then this weapon would have a Quality rating of 65%