To get a better performance, we make different grades for milling and drilling. Carbide grade BT45, BT50, BT55 and BT60 are for milling. And the BL510 and BL610 are recommended for drilling, the slight difference between the two grades is BL510 contains the element TaC which make it super good for machining the metals which cause temperature very high during machining, the stainless steel 316 and 304 are belong to such materials. For drilling other metals, BL610 is more recommended.
Advanced carbide drill bits with coolant holes(straight hole or holes, helix holes) are more and more popular in the market, both BL510 and BL610 can be made to be carbide rod with coolant hole(straight hole or holes, helix holes) to meet the material requirement of internal coolant carbide drill bits.
Below are the physical details.
For general drill bits,end mills with coolent holes.
For drill bits drilling stainless steel such as 316 and 304, or for end mills with coolant holes.