Originally Posted by
TGS
And to add on/clarify the extreme other end that equation that represents low end brands, they just get whatever is shipped and don't even know the specifications themselves because none were set. They may be buying components from the same manufacturer as another high end brand, but they are commonly buying reject lots that didn't meet specification. They're just looking for X number of component for Y price, and those specs such as port size can change from lot-to-lot.
Perfect example: Palmetto State Armory has great customer service and wanted to answer a customer question on ARFCOM about port size for a specific SKU but didn't know the answer, so the CS dude asked the technical guys, who also didn't know. They just simply didn't know what they were buying, because there was no specification at all. That tells you more about the quality of the product than the actual answer of port size.
And that's how you're able to get an assembled upper for $179, and why it just might not be the equal of an upper than costs $800. (To be clear, I'm not a hater, I own both :) )