Additional physics describing fishtailing:Physics Time! The fishtailing that you notice is the result of a stable front-point, on the dart, combined with an unstable and irregularly shaped length trailing behind it.
Would the heavier weights on the CDTS's fix the "fishtailing" problem that I, and presumably others, have been having? I've talked with a few friends who I thought would know better than I and have gotten mixed thoughts, some say more weight at the front, others say more at the back.
Basically, the weighted front-end of the dart wants to remain in a single projected line, due to a strong moment of inertia. However, the length of foam behind it doesn't have the mass to affect a suitably strong inertia. As such, the passage of air over the foam causes the body of the dart to spin and move. Since the front end of the dart is set into a ballistic path, the weighted front-point acts as a fulcrum for the lever that the rest of the dart has become. The tail of the dart then flails as far as it can from the fulcrum point until the forces acting upon it change and cause it to move in another direction.
And that's fishtailing!
Fishtailing is also a symptom of having a too-short barrel. In the Longshot, it's reasonable that removing restrictors could cause fishtailing, as there's now extra power in the same length barrel. Fishtailing can begin because there is additional pressure that needs to be vented before the dart leaves the barrel. Optimum circumstances are that the barrel pressure is equalized when the dart leaves the barrel. However, if there is still high pressure, there will be a puff of air behind the dart as it leaves the barrel. This will cause the light rear end of the dart to sway to the side. The heavier tip will be unaffected, and will continue to pull in a straight line, causing the rear to wobble back and forth until equillibrium is reached and the wobble stops.
The usual cure to fishtailing is well made darts, but also either a longer barrel, or venting before the end to allow extra pressure to bleed off.