A little helical or even a slight offset would be better than straight. I mean, would you shoot a rifle without any rifling in the barrel? A little offset with mechanicals gives it just enough spin to keep it straight and steady. The bitz is a good jig. Also, you might want to look at a jo-jan. Its all preference and there both good. But, you really want to consider putting a slight offset or even a helical. If your shooting carbons, go with offset(better clearence).