I finally got a crossbow

[Cossack]

Congrats, I had to go to a horizontal bow myself.
Because of their speed and short arrows (bolts) x bows are a bit different. Try shooting the smallish 4 sided broadhead like Slick Tricks. Their 100 gr magnum works for me. The smaller diameter and 4 blades prevent the bolt from being steered by the bh. And they tend to shoot to the same point as field points of comperable weight.
Lacking knowledge I experimented, starting with the larger Thunderheads. Lack of accuracy cost me 2 bucks. ST's cured that problem.

Here are several X bow sites you may find helpful:

http://www.archerytalk.com/vb/forumdisplay.php?f=46
http://www.huntingnet.com/forum/tt.aspx?forumid=96
http://www.excaliburcrossbow.com/php...wforum.php?f=1