[Yo-Yo]

The receiver is the serialized part, and you'll have to either purchase or fabricate one.

Then, you still have to make sure your completed gun complies with 922r, so you're going to end up replacing several of those parts from the kit with US made parts.

[Kartographer]

I think I skip it. By the time I get a receiver I could buy one for just a bit more and save myself the trouble.

Boy I wish I had brought a second one back when they were $349, they are $599 now.