This strongly worded post from respected Evangelical scholar Ben Witherington is worth considering (read it here):
To my fellow Christians that like to think guns and Christianity go well together - enough is more than enough. You are living in denial of the Gospel, and its time to grow up. 'Thou shalt not kill' does not have a codicil of addendum to it which reads 'except in self-defense' or the like.
My views on gun control have been in a state of flux since Tucson. I still consider hunting a legitimate use for guns, even if it's not something I'm interested in. Beyond that, though, I'm having an increasingly difficult time justifying the private ownership of guns explicitly designed to kill people. Witherington does a good job of addressing the usual argument against gun control in the post.