[mambro]

I don't think the issue is with the threaded barrel so much as what one may attach to it. While not exactly a direct answer to your question, this company has a good description of the legality of suppressors and the legal process along the way to ownership:

http://www.advanced-armament.com/owners.asp

I have seen threaded 9mm barrels for the P99 for sale on eBay (of all places) as well as on other forums, with no mention of NFA requirements.

Since I am looking for a P99 .40 S&W threaded barrel I'll ask... are you buying or selling?

 

[mambro]

BTW, there are at least two other options to Earl's that I know of:

Jarvis:
http://www.jarvis-custom.com/Product....lt.aspx

Bar Sto:
http://www.barsto.com/category_main.cfm?ID=WSP