The existing one has 2 pins . One by the bayonet , the other by the sight . At the lug- I knocked that pin up from the bottom, as I wasn`t sure if it was tapered .Both pins were easily removed. Now the pins being out It simply would not budge even using a jig and a vise. Impressive. I didn`t want to apply heat so I clamped it in the vise ( with protection) . Using a large flat file simply file the underside of the piece flat. As you are doing so you will start to see the barrel appear. Just move along until the barrel line runs the whole length. It only took about 15 minutes. Now it taps off easily.
To install the new one I lubed it a little. I drilled a hole in a block of hardwood to fit over the barrel end and with a few good taps it went on. At one point I thought I might have to remove it again and gently and evenly run the file around the barrel , but it did go on. The lug pin went in the old hole . The sight pin I had to run a drill bit through. I had to file the dovetail slightly to slide the sight in place. The bayonet installed easily. The whole project took about an hour. Hope that helps and good luck.