Back half of the ramp is a bit long and plain. I started to rib it. 16 lines per inch. An expensive checkering file is not needed. A simple bolt threading file works fine to start the grooves and nearly finish them. The final touches come later, pointing up the tops of the ramps and the bottom of the grooves with a simple triangle file. Enough for now. Much more draw filing to do on the barrel to remove some or all of the pits and there's still that pesky grip frame conversion....