No more boppage was really suggested than the hits to remove or install a front sight, hence the Godzilla point. Might depend on the distance of crown from the holding medium, but there are holding mediums and then there are better holding mediums(stout barrel vise and bushings that fit) versus vise..........just an example/thought.
Use of a hammer is kinda an acquired talent, lots of folks use a hammer and mandrel to install front banded sights on hunting rifles; others use a lathe and boring bar, but many are done with hammer hits on a tapered mandrel.
I know some use extra precautions on working on firearms, such as a mandrel in the bore during certain operations, to each their own there. If you can remove the mandrel at the end of work, then one has to wonder a bit. Being an old benchrrester, it is an acquired thing; usually not on 500 dollar blanks though......at least not right away....
