RE: Building a Gun?? How Hard?
You can do a pretty good job of getting a true custom with handtools going the Savage route. I think their actions are available as separate components. Shilen makes a screw on barrel. Boyd's, McMillan, Bell and Carlson, as well as others all make stocks. Jewell, Shar Shooter's Supply and a few other's make triggers. There are also a few good scope bases, TPS, Warne, etc.
BTW. . .It is fairly hard.