RHClark is spot on. Has been my experience as well.
That is why I like carbon, can tune them to perfect bare shaft flight. I have shot bare shaft carbons out to about 40 yards. It is pretty cool when one can stack bare shafts on top of each other at that distance.
If you want heavier arrows, cut them a little shorter and increase insert/point weight. Likewise, you can leave them longer and go with lighter inserts/points to decrease arrow weight.
Have never had any luck trying the same tuning procedure with wood arrows, in fact, pretty dismal results. Have never messed with aluminum.
