go with the Hammerhead Bangstikx barrel, I have the Recon as well as one of my teammates and they do us good, and honestly the flatline is only good for a small amount more range from what I got out of it and accuracy is nil in comparison.
The Sharktooth I have only managed to test a little bit, but its pretty dang good on the accurate side, and anyone getting shot by you with it will know for sure its you! that little sucker is loud!