If you are talking about using 2 pins as "dowels" parallel to the bore and internal, then this definitely works.
Before installation of the horn tip, it is easier to get the barrel channel profile established in the horn and establish a good flat surface for the wood to horn junction.
I just did a tip about 3 months ago, and used 2 internal dowels. I drilled 2 tiny pilot holes at the desired location, and inserted 1/16" brass nails with the heads removed, and the sharp portion protruding. I installed the barrel, and merely slid the nosecap along the barrel underside until the sharp points made an indentation on the wood stock. I then removed the pins, and then punched out the proper diameter for the dowels.
I used dowels made from box wood, because box is extremely strong, stable, and glues very well.
When I was final sanding, the stock slipped and smacked the tip very hard on the edge of the bench, and it was not even fazed. Unbelievable.
You can also hollow out the horn and slide it over a male section of wood, but by gluing it to a flat, the glue line can be perfectly straight and even. since horn is not heavy like brass or "pewter", it can be left solid without adding weight.
