Consider the statement that for the Magnus Effect to be present, a cylindrical projectile spinning about its axis MUST be in the" Yaw of Repose".
The Yaw of repose is typical of bullets/projectiles which are NOT drag stabilised.
Pellets ARE drag stabilised, like an arrow, or bomb with fins, or shuttlcock.
I think the key difference can be found in whether the " centre of pressure" lies before or after the "centre of gravity". Namely, is it drag stabilised or spin stabilised?