Its amazing the poor quality of rings out there I just finnished last night doing 5 guns for friends and one of my own. I had 30mm Hart rings I put on my 700 rem 7mmwsm they where the best of them all only took a lttle time my brothers took over a hour steel very hard.and badly shaped. The unite I bought has two grits they supplyed 320 grit for alunimum & 240grit for steel
good luck
