Hello my friends, i would like to know more about the D bits and can anyone help me? I need to drill a long straight and concentric 16" hole and the best way, as you may already know, is the famous gun drill. however, I was looking for a cheaper alternative to carry out the process (many will say that the gun drill is very cheap and viable, of course, for those who live in Uncle Sam's land. In my country, the dollar is worth five times our currency, apart from the import tax that charges 60% and the freight. It's not feasible) and I heard about the D bits. But some say it sticks and others say it doesn't. after all, does the D bit make a nice deep hole or not? best wishes to all