What Giz sez is correct, Taff. However, one must decide for himself whether it is in his best interests to jack around on doing it himself or having someone established do it.
For me, it's about the time. As time=Benjamins=bling, bling=attention from da hotties, I just UPS them (use the line!) to Arkansas and let them deal with it. I: 1. don't have time; 2. wish to use that time shooting, 3. would rather pay than use time.
I also like having a business relationship, it saves me time and grief via delegation. The fact that I am a known customer and if I need anything I can call helps reduce stress is my world.
Giz is right, you can do it yourself or if you know a gunsmith have him do it. I prefer this way.