Most builders will build with either swamped barrels or straight barrels, unless he possibly is building a particular rifle that requires straight barrel, or the builder just doesn't want to pay the price dif.
I did one time run across a guy that was going to take a straight one & swamp it ...... that lasted one flat & he was done with that idea. :rotf: Any swamp you could really notice with the naked eye would take some serious filing...... hours & HOURS of filing..... :shake:
A weight barrels require more critical work (IMHO), as if you have anything forced at all, it will deflect the barrel. I can lay a A weight .40 cal barrel on a table & see it flex using my little finger, that is how easy they flex. Tho I have used them, I prefer to not go past a .36 cal in a "A" weight, and .40 go to a "B" weight.
For those not use to building allot, I suggest ya use a "B" or "C" weight barrel. A Green Mtn. A weight barrel is considerably stiffer than a Rice or Getz or Colerain, as the steel in a Green Mountain is a dif type of metal. You may not notice it allot during the build til you cut the dovetails or engrave on one, then you can really tell the dif.
Keith Lisle