How about trying some factory match ammo? Gold medal match or M118.
Not saying your handloads are the problem. Just trying to remove variables. 147 ball usually isn't anything but blasting ammo.
You need to figure out when the stingers become subsonic. The transition between supersonic and subsonic upsets the bullet. If you stay subsonic the whole way you don't have that problem.
That's the bad thing about 22's. What ammo just stacks them in a tight group in one rifle will look like a shotgun pattern in the exact model but a different gun.