Years ago, a single knife "moulding head" was available through Sears (Craftsman) in which a variety of 1" profiled moulding cutters could be utilized. The head was "balanced for the single knife - it could be used on either a table saw or a radial arm saw. After this was marketed, Vermont American marketed a 3 knife head - the moulding knives were identical to the Sears knives. I have one of the Sears single knife heads and I made different size cutters for inletting straight octagon barrels by profile grinding the 1 inch cutting knives that were straight and designed for cutting either a 1" dado or for cutting half lap joints on board edges.
I mount the moulding head in my table saw with a throat plate that I made for it. I clamp a hardwood fence so that the stock blank will feed between them with the cutter in the correct position in the stock and after I've marked the stock where I want the barrel channel to end at the breech that corresponds with a mark on the fence where I need to stop, I make three or four runs, raising the moulding head each time until the barrel channel is cut to the correct depth.
This has worked well for me and then the only hand work required is to finish the inlet at the breech area to remove the radius formed by the cutter. Before making any runs on the stock, I make a sample cut on a piece of wood the same thickness as my blank to double check my alignment and depth.