The final vote, taken at about 4:45a.m., not only bans firearm build kits, but also effectively bans possession of completed guns made from parts or build kits.

Beginning 180 days after the effective date of this amendatory Act of the 102nd General Assembly, unless the party receiving the firearm is a federal firearms importer or federal firearms manufacturer, it is unlawful for any person to knowingly possess, purchase, transport, or receive a firearm that is not imprinted with a serial number by (1) a federal firearms importer or federal firearms manufacturer in compliance with all federal laws and regulations regulating the manufacture and import of firearms or (2) a federal firearms manufacturer, federal firearms dealer, or other federal licensee authorized to provide marking services in compliance with the unserialized firearm serialization process under subsection (f) of this Section.

Then about the Uppers:

Take for example the prohibition of unserialized frames or receivers. The bill's definition of a receiver . . .

"Frame or receiver" means a part of a firearm that, when the complete weapon is assembled, is visible from the exterior and provides housing or a structure designed to hold or integrate one or more fire control components, even if pins or other attachments are required to connect those components to the housing or structure. For models of firearms in which multiple parts provide such housing or structure, the part or parts that the Director of the federal Bureau of Alcohol, Tobacco, Firearms and Explosives has determined are a frame or receiver constitute the frame or receiver. For purposes of this definition, "fire control component" means a component necessary for the firearm to initiate, complete, or continue the firing sequence, including any of the following: hammer, bolt, bolt carrier, breechblock, cylinder, trigger mechanism, firing pin, striker, or slide rails.

Based on that language, it looks like your modular SIG SAUER P320 and P365 pistols will be banned unless the grip assemblies are serialized by an FFL.

But wait, it gets better. A reasonable reading of the bill would likely ban pretty much every AR-15 in Illinois, too . . .

For purposes of this definition, "fire control component" means a component necessary for the firearm to initiate, complete, or continue the firing sequence, including any of the following: hammer, bolt, bolt carrier, breechblock, cylinder, trigger mechanism, firing pin, striker, or slide rails.

That sounds like AR upper receivers will now require a serial number, as well as the lower. That's something very few upper receivers (if any) currently have. Will buying one in Illinois now require a background check/FTIP check? Will a FOID card be required to possess one in Illinois?

“Frame or receiver” means a part of a firearm that, when the complete weapon is assembled, is visible from the exterior and provides housing or a structure designed to hold or integrate one or more fire control components, even if pins or other attachments are required to connect those components to the housing or structure. For models of firearms in which multiple parts provide such housing or structure, the part or parts that the Director of the federal Bureau of Alcohol, Tobacco, Firearms and Explosives has determined are a frame or receiver constitute the frame or receiver. For purposes of this definition, “fire control component” means a component necessary for the firearm to initiate, complete, or continue the firing sequence, including any of the following: hammer, bolt, bolt carrier, breechblock, cylinder, trigger mechanism, firing pin, striker, or slide rails.