I have a 29" draw length, 70# draw weight, 80% letoff, and shoot 350 grain arrows. What broadhead grain should I use and why? I have been shooting 85 grain Grim Reapers. What difference would it make if I switched to 100 grain?

You wouldlose about 5 fps in speed and pick up a couple more pounds of kinetic energy.

How could you gain speed if the broadhead is heavier, more energy yes, was that 350grains total with the head of 85gr on it or by the arrow itself? You'll gain penetration.

Ha Ha I typed it in wrong and adjusted it before you posted. Quick thinking on your part, not proof reading on mine. I tend to act before I think sometimes.[8D]

I was wondering, if that was the case we all would be using 210gr broadheads. No harm no foul.

350 w/out the 85 gr

Believe it or not you may have just found the perfect blend of speed and penetration. Go with the 100gr head. My arrows are a total weight of 441 with a 100gr muzzy. My arrows are only 27.75 in long and I blow through everything and stick into the ground 8 inches. Your probably going to be around 6.2 to 6.3 grains per inch enough to put down a moose. You'll get more penetration hands down and could shot the deer practically anywhere and pass thru him. As with any changes make sure the broadhead flies true, you'll find out that your old one may not fly the same. Your pushing enough energy that you could use a mech. effeciently, but check into muzzy's , magnus stingers, steelforce. Muzzy's are sometimes harder to tune, but the other two most of the time shoot just like your field points. Plus with the 100gr it's still going to shoot flat out to 30 with one pin depending on your setup. Going heavier might be the best thing you could do. Some will say there will be little difference between the two, but 15 grains could mean the difference of coming home empty handed, don't get me wrong a well placed shot will kill, but if 85's were better for me I'd be shooting them.