I recently purchased Alaska Bowhunter Supplies Grizzlystik carbon shafts. As far as heavy and tough goes, these shafts are hard to beat. I'm shooting the 15 grains/inch shaft and my total arrow weight at 29.5 inches, with a 75gr. brass insert and a steel broadhead adapter in a Wensel Woodsmen, is 800 grains.
The entire shaft is tapered from the nock to the broadhead, with the nock-end using a 9/32 nock, and the front end being slightly larger in diameter than the broadhead. However, the brass insert is tapered to match the diameter of the broadhead.
For some, the larger outside diameter goes against the theory the shaft should be smaller than the broadhead, but I find the flight characteristics and penetration outstanding.
I'm totally satisfied with these heavy carbons and I will put them to the test during a black bear hunt in Northern Saskatchewan in a couple of weeks.