TooBigToFit
Well-Known Member
It’s the lower receiver or portion of firearm with the trigger that is technically considered the weapon, all other portions are considered components (to include barrels). Manufacturers put the serial number on this portion but it is illegal to ship this portion (part with trigger assemble or where trigger is located) of a firearm without going through an ffl to transfer, such as lower receivers, pistols frames. Actions can be shipped without going through an ffl, ex being complete upper receiver, bolt actions without triggers attached, pistol slides etc..
Sent from parts unknown
It is not always the portion with the trigger that is the receiver. HK G3/HK33/MP5 lower frames contain the trigger, but are not considered the lower receiver. You can buy an HK G3 trigger group, with full auto parts, and have it shipped to your door like a pair of underwear from Amazon.