I used this to drill the trunnion and barrel for the AK barrel pin. Made my job easier. With things like this killing even the most expensive drills, it's nice to be able to buy a big pack cheaply and throw them away after every build. It is important to remember the drill speed and feed rate. At first I tried to dive in too quickly and it didn't work. I then applied light and slow pressure with the bits and they did their job with ease (with the help of cutting fluid).