Typical Carbon arrow weight, and by that I mean the standard 5/16 O.D. carbon size runs around 8 grain per inch, with components (vanes, nock, and insert) you are probably adding another 40-45 grains, then add your point weight and get a total.

I shoot a 28" carbon at 8.2 gr./in. so thats 229.6 + 42 (nock, insert, blazers), and 100 gr point for a total of 371.6 grains.

With that set up shooting 70lbs I would be at 5.3 grains/lbs, which like Waltwittman says is pushing it a bit, so I added 3 gr/in. weight tubes which, after cutting to fit between insert and nock, add another 81 gr bringing me to a total arrow weight of 452.6 gr.

With that weight at 70lbs I now have 6.4 gr/lbs.I have not compared the speed variance of the arrow with and without the tube, however, I am shooting forpenetration and I sure do like the KE I get with that setup.

If yer gonna hit em do it with aMack truck - not aTonka truck!