Nerf compatible half dart 3d print

Recently I've been trying to make a 3D printed gun for Nerf. But I had a lot of trouble finding darts that I could 3D print that would work. So I decided to design one myself the main problem I was having is they didn't fly straight they would tend to flip over in the air this was battled by weights at the front in actual Nerf bullets but I didn't have that so what I did was I had it some fins to the back which should give the same effect as rifling on a real gun and these shoot pret