"the energy of an impact will be much more direct transfer of energy onto the wood"

But it's spread out over a larger area. I've done that for FOC reasons only, not durability but they seem to be better then "normal" tip arrangements. For durability the arrow would be footed. I don't epoxy them in, I use super glue. They are easily removed by touching the metal with a soldering iron and if done right, the super glue turns to gas and literally "spits out" the metal insert while epoxy gets gummy and requires a lot of twisting and 4 letter words to remove.

"uses tungsten rod inserts, which have the double advantage of being much heavier than steel,"

Yep, mostly 1/8" stuff in tungsten, steel (music wire), or brass. The 1/8" tungsten is about 60 gr/in...O.L.

O.L. where would one find the tungsten wire. I like the idea of drilling a smaller hole.
Jack

Jack, there are several sources that a Google search will show up. Here is the place I've bought some from:  http://www.buffalotungsten.com/html/tungsten_rod.html

Hope that helps...O.L.

Thanks O.L.