"Constant heavy pressure"...I disagree.
Constant pressure, but not heavy.
If you are gentle, your bit will do the work & last much longer.
Be sure to use a lot of cutting oil.
I did my two 60 qt kettles & it was much more intimidating than it should have been.
Just be sure you don't put the spigot up too high.
If you are going with weldless fittings, figure out how much clearance you need for a washer & go just a little beyond that.
Of course, if you're using a false bottom, that may create a different situation.
I only use braided line or an improvised bazooka screen, so that wasn't an issue, for me.
Still...I drilled both kettles about 1/2" too high.