I am gunsmith/CNC machinist. I make a muzzle breaks for rifles and need to see some thoughts on drilling and threading. Currently I have a CNC Masters 1440 Lathe and a Tormach PCNC1100 mill. The lathe will drill a very nice straight hole through 4140 steel if I first start the hole (21/64 for .308 bullets) with the tail chuck and finish the 2.5 in deep hole with chuck in the tool holder. Then Change to 29/64 drill started in the tail chuck and finished 1.4 in deep with drill in holder. The table and cross slide can't start a good hole(flexing and moving). I then finish with 1/2 x 28 single point thread .55 deep. They come out just fine but take a long time to make one. My question really is can I get the same level of concentricity with the mill. I am familiar with thread milling. It seems as it should and take half the time.