This is a pure brass rod with a flat base that is meant for seating and shaving bullets to get them to pass through the loading port. It is required for most bullets when using most conical bullets the .44 Colt Navy replica, and in some Dragoons and Walkers using many of conicals out there.
Do not be concerned about damaging the point of your conicals with either this tapping rod, or the Pietta loading lever rod, which notoriously does not have a cup in it like the Ubertis. The base of the bullet is what steers it, not the nose.
The most popular target bullet for a .38 Special is called a wadcutter, and is perfectly flat, with no point at all.
To prevent any deformity from loading conicals in your cap & ball revolvers, you would need an actual top punch designed for that specific bullet, and it would have no effect on accuracy regardless.
What causes inaccuracy in a cap & ball revolver is that the bullet is not perfectly centered when it shaves. This will be true of any conical that shaves, except the bullets designed specifically for these guns. They have a "skirt" that holds the bullet in the center while you compress.