I recently had a customer with a deep hole drilling problem. He was trying to drill a 3/4" hole in low carbon steel 10-1/2" deep on an old drill press. He was originally looking for a taper shank HSS drill in an extra long length. After discussing the application, I suggested using an Allied spade drill with a helical flute (the tool was rotating in this instance so the helical flutes help with chip evacuation) and an MT3 shank, equipped with a coolant inducing ring and a TiN coated T-A insert. He was able to drill all 6 holes (63 linear inches) with a single spade blade. The spade drill ran much faster than a standard twist drill and the coolant inducer greatly reduced the need for pecking.
Do you do deep hole drilling? What has worked for you?