Probably not new to this forum but I think that we found a really tough stump shooting carbon by doing some modifications. Leon Stewart and I were fooling around with making me a half dozen carbon stump shooters a few weeks ago. We took a 3/8 oak dowel rod, cut it down to 6 " and sanded it down to fit a 35/55 Carbon Tech Whitetail carbon shaft. We glued in the wood dowel rod and then I bought some really nice 125 grain rubber screw in blunts from a local archery shop that have a large round head. I normally shoot 175 grain field points and they fly the same with this configuraiton. I figured the dowel rod and 125 grain tip weight out close to 175 grains on the front end of the arrow.
I have been shooting these things into everything without any issue whatsoever. It really added strength to these shafts and keeps them from breaking up front. I think the rubber blunt configuration also helps soften the blow to the front of the arrow.
Ron