Not suggesting you do this, but this is my process for opening up 4 hole stingers.
I start with a thin, flat fine file that tapers to a point, and open up the bit end slot. This step usually is the most beneficial. Next, I use a Dremel with a spherical cutter head & open up the main draft hole, following the contour of the opening. Before the next step, I scribe a line on the stinger threads & mate to the stem tennon face. This helps in reassembly).
Then I remove / unthread the stinger body from the stem with an alcohol flame lamp and a pair of pleirs with rubber or leather lined jaws.
Once the stem & stinger are separated, I grip the stinger body with a vice that has rubber faced jaws. I drill out the hole (the end that threaded into the stem body) following up to the enlarged contour hole. Then I polish the main draft hole with a bristle pipe cleaner loaded with polishing compound. Then wash out & follow with dish soap & clean pipe cleaners.
Next, I’ll enlarge the stem body draft hole & shape / contour to fit the widened button slot, then re-install the stinger into the stem & adjust to match the position of stem so when tightened, it sits correctly in relationship to the bowl (ie logo is where it should be and button is perpendicular to the bowl height. I call it clocking the stem.
Finally, I’ll drill out the sphere holes slightly to complete easing the draft. Need to do a video on this.