Barrel weight and marking?
 

How many different weights are there an where are they marked? Is an 8 one?

There are no finished weight markings on the barrels, to my knowledge. There is a weight stamp (larger number, followed by a smaller superscript number)on the underside of the barrels which is the unstruck weight of the barrels before finishing Depending on the customer's wishes, the final weight of the barrels varied, depending on the purpose for the gun and the balance desired

Well, there are 16 oz in a pound. And with pound markings ranging from 2 to 12. I suppose there could be around 160 different barrel weights.

.I've been looking around for a light 12 GA. Virtually everyone I've seen has been well over 7 lbs, I've run across one that's 6 and 3/4. I guess I'm just a bitter suspicious of how it's so light.

You want a 1 frame or 1-1/2 frame. My 1 frame 12g grouse gun is 6 lbs 14 oz with 28" barrels.