Most are reluctant to recontour barrels due to issues related to releasing internal stresses resulting in bending and warpage. Can't say that I blame them for not wanting to deal with an issue like that. By the time you pay to have the barrel removed and re-installed, pay shipping both ways and the charge for recontouring you'll probably spent the best part of the cost of a new barrel contoured the way you want. This plus not having to deal with possible bent barrel issues pretty much much makes the decision to purchase a new barrel no-brainer.
