I chuck the detent into a drill and roll the pointed tip and the cornered edge of the bevel into a nice gentle curve. No need for it to be pointed at all.
Then, similarly, I take a small tapered round file and knock the corners off of the holes at either end of the detent groove, and polish the groove itself. No reason for the holes to be so distinct, they can be significantly rounded and still positively hold the selector switch in the appropriate positions.
The problem with selectors, how they leave the factory, is in the dimensions. The detent is supported at the rim until it's able to fully drop into the detent holes, which then "snaps" it against the selector. By softening all of the edges, you can let it ride down the holes a little better without that loud "snap" at the end, but still holding in position securely.