What you are doing with a build is replacing the receiver.
You also are replacing enough parts to put you under the 10 or less rule.
I'm not so sure that "gunsmithing" is necessary, but, there are some things
that matter, like the original length of the gas piston on the carrier.
The location of the rear trunnion in relation to the front and things like that.
Reading the posts in the build forum and some of the links to sites that tell
about builds and have tutorals is helpful.
With an all matching kit, you are basically reassembling the parts that come with it.
How much you have to do and know depends on what kind of receiver you buy
and what type of build (screws or rivets).
Most that have a fair amount of mechanical ability seem to be able to do it.
Even a few that don't.
HTH
BB
