Here are a couple examples.
This one was home ground. It has a nice sharp edge and leaves a good finish.
This is a commercial bar with a carbide shank and uses inserts. It doesn’t leave as nice of a finish largely due to a very sharp radius on the cutting edge.
Advantage of the carbide bar is that it flexes far less when stuck out a long way. Disadvantage is the rougher finish it leaves.
Tool flex with boring bars is a real issue. My little home ground tool flexes a ton when cutting up to an inch. Needs to be long and skinny to make a 30 cal sizer but long and skinny means more flex.
When I bore a hole with the home ground tool I make many small cuts, maybe .002 per side at a time. When I get close I also make multiple spring passes, a cut where the tool is not moved. This means the tool removes metal left on a previous pass because the tool or workpiece flexed away from the cut. That has bit me in the ass in the pass when I ignored it. I want to cut another .002 deep but don’t take a spring pass first. That means when I take a spring pass after the tool change and initial cut I may be .004 deeper! Messed up a sizer that way the other day when a .433 sizer suddenly measured .433 and I still needed to polish it.
Polishing is done under power with a split rod, emery, and lots of oil. I start with 240 grit to remove material quick and finish with 400 for a better finish. I polish, pleas the die, hen check with a pin gauge. If I want a .433 sizer I want a .432 pin to enter easily but a .433 pin to not go in. That means I am usually .0003 under desired size. That small difference is far less that the variances in final size due to alloy changes.