There are a couple of threads about the finecasts on the site already and while most of the older finecasts tend to be reviewed poorly they aren't always this way. From what people are reporting with the newest finecasts, such as those for The Hobbit, they are coming out perfectly.
The problem with Crossbowmen is that if any of the miscasts are still in the house from when they first started to make them, you might luck out and get one of them while the ones that are more recently cast will probably not have as many or no issues. About a month ago I ordered some High Elf Spearmen and some of them the feet had to be reshaped as the detail was lost in some thick flash; but don't forget that even with the metals there were problems with miscasts from time to time.
All you can really do is get it exchanged, from what most people have said GW is really good about sending you replacements for miscasts.
Here are a few threads that talk about them:
viewtopic.php?f=30&t=22426www.one-ring.co.uk/viewtopic.php?f=30&t=24548