Daryl,
When I built the gun, about 15 years ago, I bought two 1 1/2" x 30" uncontoured barrel blanks from Hastings. At that time Hastings was making their own barrels in the USA and had a very good selection to choose from. It is my understanding that they have their barrels made offshore now, and they only have 3 contours to choose from, with rifle sights, with scope cantilever, and with dangerous game type quarter rib. The twist is 1 in 48", the bore diameter is .712", and the groove diameter is .720". I regulated the gun with Lightfield, Hybred Sabot, 1 1/4 oz slugs. I bought what I felt was a lifetime supply of them at that time. This slug has an attached plastic base wad, which stays with the slug all the way to impact. The gun has a 1/16" silver bead, and a flip-up 1/8" ivory bead on a front ramp and a shallow V rear sight. From a supported shooting position, I can generally put two lefts and two rights into 1 1/2" at 50 yards. I've killed about a dozen deer with this gun and I can say that these Lightfields are accurate in flight and devastating upon impact.