AK-47 Parts Kit with Auto Sear Legality?

[Orion]

Thanks Quarterbore. That raises a couple other questions.
I notice that if I buy a receiver already bent, welded and heat treated it is subject to being registered and transferred by a FFL holder. If I buy it as a predrilled/milled blank and bend, weld and heat treat it myself does that receiver have to be registered after I am finished with it? Is it subject to the $200 firearm manufacturing tax?

I was surprised to see that you live in Valley Forge, I am in Limerick, just up the road from you...