Mori, welcome to the site!
The sheet metal nose cap is fit by carefully removing wood until it seats at 90 degrees to the barrel, and with a very slight gap between the cap and the end of the rib. You just cut away the wood that is replaced by the steel sheet cap. On my last one, I doubled the metal in the rod groove, and used a small 6x 40 screw with a large head from inside the barrel channel.