I have a new bowhunter friend(15 yrs old) that just purchased a new Bear Grizzley. Try as I might I can't seem to get it to shoot softly. It kicks like a mule! I have tried the string lengthening and B50 and FF to no avail. Should I lighten up the tips? I dont want to mess up his bow, but it just aint right the way it is.

What weight are the arrows?

Did you try adjusting the brace height.  That's what I'd do first, fins the sweet spot, then play some with heavier arrows.  I wouldn't do anything to the tips, the minute amount of weight lost won't amount to much when it comes to handshock.  
Mike

I disagree, Removing wt. from the tip can make a huge differance. However, I would try all other options first unless you are comfortable doing this kind of work.

The arrows are total 450 460 gr wood with points.We have also tried aluminum 2115's.I have some 2219's but that seems too heavy for 55 #
Tried string heights as well.
Thanks for the replies.
Dan, I have built a few bows and Think I can take the tips down. If it were my own, I probably would have already done so
Thanks to all for your input