Thanks for the pics.
I'm not sure about the legality of a non-serial numbered receiver here in the US.
The receiver is what the ATF considers to be the actual firearm.
Anyone else know about the legality?
As nice as it would be to be able to buy P99 frames, to do so would violate US law, unless it bears a serial number, and the transaction is conducted through a licensed dealer. The construction of the P22 frame is wildy different from that of the P99. The P99 does not have any sort of insert that bears a serial number that could be considered the *real* frame. Knowing this distinction is certainly prudent.
For example, if you were to live in a country whose laws don't consider the frame to be the firearm, such as South Africa, there would be no problem buying these P99 frames. In South Africa, however, the barrel is considered the firearm, and has simiilar restrictions like frames in the US (must bear a serial number, and so on).