Effectively, as your Project Manager says, a micro-inch is 1/1000000 of an inch (the meaning of the prefix micro is 10^(-6) wich is the same as 1/1000000). In such way, 500 micro-inches are 0.000500 inches (not 0.000050 inches as you posted), wich is a tipical value that you can obtain with flame cutting. The tipical range of this manufacturing process by common production methods is 500-1000 micro-inches. If you have the correct AWS sample you can visually (and easily) determine if your surface preparation is correct, I meant if it is cumplying with the required roughness.
I hope this help you.
Jorge Giraldo
MedellĂn, Colombia