I have several sets of Redding FL and NK bushing dies, along with RCBS benchrest, Lee, Lyman, Hornady etc. I like the bushing FL dies best as I can adjust the amount of shoulder push back by using competition shell holders, the NK dies won't tough the shoulder, at least all the bushing NK dies I have now, 223, 243, 7mm-08, 308, 300WM. I also found the bushing FL dies only resize the bases 0.004" to 0.006" so maybe my chambers and the dies fit better than others. I don't use the expander button on any of the bushing dies and polish the buttons down to fit better on most of my other die sets. Some of my wildcat chambers are short and some are long in relation to the sizing dies so the competition shell holders make it easier to adjust the dies to the chamber. I have found that there isn't one way only. Each rifle has it's own way of doing things. The Hornaday seaters never were consistent in the amount of runout and usually the runout was way beyond what I consider to be close enough, i.e. < 0.003" for varmints out to 5 or 6 hundred yards. I have at least 8 sets for rifle and piston and don't bother with the seaters now. I do like the sizers and the elliptical expander, but again, for close work I use a benchrest type of seater.
If you can't get things to work out try making a chamber cast and measure everything. Weight the cases also. I'm having some trouble with a 223 not grouping. I an using IMI cases and was getting groups around 1.25" with flyers. I had weighed some cases earlier and they were running around 94.5 gr after trimming, turning and primer pocket uniforming but them one would go 91.7 or 96.8 so out of 50 I ended up with 30 weighing from 94 to 95 gr. I shot a 5 round one hole group that was a .150" with Barnes 40gr VLS, 27.5 Benchrest, Rem 71/2, seated 2.180" which is 0.020" of the lands. That's what the Ruger SS was shooting before I changed cases. It doesn't take much to make the groups open or close. Lots to learn and the information is available just watch for the egos and check any loading info before you try it.