Question on building pistols from parts

[redneck]

I keep seeing these threads on you fella's souped up 1911's an high powers, and all the other toys. Most of them seem to start out as a kimber or colt or something that gets totally replaced with a lightweight grip frame, tighter slide, tool steel internals, match grade barrel, and custom grips. Seems like there is absolutely nothing left of the original gun.
Which brings me to the question of which part is considered "the gun", like if you want to build an AR15 from a parts kit you can get all the aftermarket stuff with no hassle but the receiver is serial numbered and requires all the legalities of buying an actual AR15 (or so I've been led to beleive).
What do you have to have that stops you from just building a pistol from custom parts rather than doing all the upgrades to a production peice ?

I guess this is kind of a dumb question but I don't know enough about handguns yet to know if there's something obvious I'm missing.

Thanks

 

[Backwoods]

The receiver with the serial # on it is the "firearm" according to the ATF. Same situation as the AR15 in other words. Everything else is just "parts".

Don in Ohio

 

[redneck]

Thanks
Now I just need to know/find out whats considered the receiver on a pistol then Nobody ever mentions that.
I suppose it would be the peice that the slide and barrel are mounted on/in huh ?

Now I feel stupid :banghead: aint the first time

 

[Hkmp5sd]

It depends on the model of pistol as to which actual piece is the receiver. In most cases, it is the frame.

Just decide what you want to build and start ordering the parts. The piece they won't send you without a FFL is the "receiver".