That looks like the result of using a die grinder with an abrasive wheel. There are several places where you can see skip marks where this "pro" let his "tool" slip out of the "port" and ride down the outside of the barrel.
Sheesh... lots of quote-unquoting there. . . Probably would have looked better if he's used a hack saw.
Looks more like a 91/2" grinder...is there any reason theyre not the same size?....shape?