It used to take a lot less time before Nauti talked me into doin' 7075...

Now,...it's hot. on. the. street. so every pair since, has had at least one 7075 block involved...

Given the depth of the holes, and the hardness of the material, and given the fact that my mill is a little light in the a.., I have to step them up in 1/16" increments, starting with 3/16"... I haven't timed it real close,...but it seems like forever...
6061 is more like, 1/4" to 1/2" to 5/8" to 23/32" to 47/64"..... Much quicker...
Brass is about like the 7075, not because it's hard, but because it likes to grab bits, if you try to take too much at once...