IF? -- paulsen, are you aware that there is no "IF"? Any citizen of the USA has the right to "build rifles".
Oh, and what about Bob Smith? Certainly he must be allowed. Bob Johnson? Bob Washington? A thousand Bobs? A million Bobs? Looks like "substantial effect" to me. How do you propose avoinding that?
Bizarre bobbie asks another weird question.. -- Why should "we" want to stop a million Bobs from making their own rifles?
Get a grip bob.
That depends on who "we" are. If "we" are career beltway bureaucrats, then "we" get more money, power, and toys.
As Inspector Clouseau said in response to "But that's a priceless Steinway" -- "Not anymore."