Glad to hear they are shooting straight.
Have you checked to make sure the bullets are not pulling out of the cases under recoil? Shoot 5 then see if the 6th bullet has moved forward.
Neck tension might be enough to hold them, but don't be afraid to add a light crimp with plated bullets. I crimp mine and it hasn't caused any problems. Recovered bullets show a crease in the plating at the crimp line, but no peeling or other problems.
Jacketed data has proven to be more consistent with the speeds I'm seeing on the chronograph using plated bullets in all my handgun calibers.