David R - This was a Rice .50 cal barrel made of 12L14, I'm sure. I have also made another tool and done the .54 cal Rice that I used for the "Kibler Copy" rifle. Both cut easily and smoothly with this tool design. I have not tried it on 8620, but the relief angle on the cutting edge is only about 4 degrees, so I would not expect any trouble with almost any common barrel alloy.
Tom - No product coming here...To make these one at a time would not be worth the effort and to set up to make anything like an economical lot would leave me with a huge number of unsold crowning tools. I posted this so anyone who needs one can make their own.
Jim K & Taylor - I agree...too much radius. On both the barrels I did, I was trying to eradicate the heavy 45 degree chamfer that Rice put on the barrels at the factory and blend it into a nice smooth radius. I will see how these barrels load and shoot. If I don't like it, I will trim the muzzles back some, but I don't think it will make much difference except for the aesthetics. A few years ago, I tried the much longer conning that caught my eye at the time and used these tools that I had ground:
The spiral one (right hand cut, left hand spiral) worked much better than the straight one that I copied from a drawing that Peter Alexander had put in an article he wrote for one of the BP magazines. (I knew it would work better than the straight cutter, but I had to try). At any rate, I have used the spiral one on several rifles....the brass pilots are interchangeable.... and it works great. I don't want to open the "to cone or not to cone...that is the question" debate here, but it has worked fine for me. However, I think I like the short, smooth radius better now.
Mark E - Rings on the muzzle are easy...just need to grind a simple cutter with one or more points, mount it in the tool, and twirl it around.