arrows striking riser?

[Orion]

Yep.  At 27-28 inches, the shafts are borderline stiff.  Heavier heads should straighten them out. BTW, if your draw is 27-28 inches, why are you shooting 31-inches behind the point arrows? Most folks leave about an inch overhang past the riser, plus point.  Could take a couple inches off the length.  That will make them (dynamic spine) stiffer yet, of course. Folks shooting carbons tend to accept that they'll have to shoot longer lengths because there isn't a lot of choice with carbon spines.  If you shoot aluminum, you don't have to.  Just get a lower spined arrow.  Good luck.

[Jake Diebolt]

Orion, the reason I shoot them so long is I was using leftover arrows from my compound shooting, when my draw was about 29". So when I got new arrows, I cut them to the same length (not knowing that that affected spine). I figured that I would draw shorter when I started shooting and eventually get to a longer draw length, so I left the arrows long - better too long than too short. Then, when I found out that shortening arrows stiffened them and changed their flight, I figured that I should leave them the same as long as they were flying OK, as I didn't want to affect the spine.

I suppose I could get a weaker spine and cut them so they're not so long, but aside from the look of the thing having long arrows shouldn't affect much, right?

[Orion]

Right.  If they're spined right for your bow, having more arrow hanging out won't make any difference. The few extra grains of added weight (20-40) won't matter much either. I prefer to use shorter arrows because they're a little easier to maneuver in tight hunting situations (on the bow or in the bow quiver).  Also, if in a bow quiver, they're a little less likely to hit brush on the nock ends when moving through the woods.