You haven't run the plugs in the first two pictures long enough to tell. The plug in the last two pictures is pretty close to spot on for heat range.
In the last picture, you can see the white ash on the ground strap ending about half way in between where it's welded to the threads and the open end. That's how you tell it's the right heat range. Ideally, the cutoff point would be perfectly in the middle of that distance.