It is called a banded octagon? I just could not get BFR to put a band on one of their regular revolvers. By recognizing the octagon would need to be machined in the Precision Shop at Magnum Research, I asked if they could just stop machining the octagon about 2 inches from the end of the barrel? The Custom Shop said sure and the measurement that must be precise is the inside corner that traps the ejector rod tube under the barrel. I called JRH and they said they could do it, but I would rather have BFR do the work in house.