why are metal lower receiver for m series illegal to import?
 

may sound like a stupid question but i looked hard for the answers
so i was wondering, i wonder why is it illegal to import the lower receiver
is it because you can fit it into a real gun? or they just wanna be a jackasses? (no offense if there are any people that works for the gov')

some airsoft can be considered as a replica firearm. and the lower receiver of an m4/16 is the part of the gun that contains the serial number. only the portion of a gun with a serial number is considered a gun.

Because it's cheaper to tell everyone at customs to incinerate anything that looks like a receiver, then it is to propose the budget increase necessary to train everyone on how to tell the difference between the fakes and real receivers.
It's the cheapest way to block a potential avenue to smuggle real gun parts.

The lower is restricted, in the real world it's also the lower that's restricted.

but can it fit on a real gun i wonder?

No, but it is considered a replica firearms receiver and is therefore prohibited for import without proper permits. Please see Importing Airsoft and You.

short answer; no, but that's not the point.
long answer; with heavy modification you MIGHT be able to get an airsoft receiver to fit on a real steel M4, but it's much easier to buy an AR-15 with your RPAL :p

Most airsoft guns arent to scale with real firearms (Around 1/8 less) so no airsoft receivers will not fit on real steel and further more the fucking monkey metal those things are made of wouldnt stand a chance against the force of a bullet being fired.

Non-issue. Most airsoft related importing problems are related to the interpretations of the CSBA, that airsoft guns and related gear can fall into the category of weapon replicas.

The are ways clear exeptions (replicas of pre-1898 manufactured guns usually are ok), but most of the guns in the airsoft world will have importation issues under the current laws and their interpretation.

Long story short, don't worry if it doesn't all make sense, it doesn't.