ALIHISGREAT wrote:So i was just wondering what spin rate would be needed to stabilize the First strike rounds as pictured above
No spin at all. They're drag stabilised by a hollow "foster" tail.
However, rifling serves two purposes. Stability and "averaging out" imperfection.
In this case, the fins may cause the latter.
That is, if the round is imperfect, and has drag that would veer it to one side if unspun - if you spin it, then rather than just veering off, that "veering" is averaged in all directions and causes it to travel in a little spiral (not perfect, but at least it's heading in the right direction, rather than off on a road to nowhere.)
The question here is whether the "fins/rifling" impart enough spin (if any at all) to meaningfully perform this averaging.
That I can't tell you. I'd really need to experiment with them (and I'm not paying the exorbitant prices) or see high speed footage of them in flight.
(That said, they're essentially FN303 projectiles for paintball. The military designers probably had a little idea what they were doing.)