I just this month finally got "THE" load down for my 204 nef. Nothing was really doing it until I tried reloader 10x. I found out what a difference .3 grains make in load work ups. I had been making .5 grain jumps before. When you do load work ups, my advise would be .5 jumps till you get acceptable groups then work around that number. I got my groups to .5 at 100 yards and have been enjoying  episodes of crow explosions past 250 yards!  My final load is   Reloader 10x at 26.3 grains
                                                            Sierra 32 gr blitzking bullets
                                                            Win small rifle primers
                                                            coal of 2.27
                                                            3950  fps
My bull barrel NEF has a 1 in 9 twist. These are max loads in the Sierra book. Nothing else was grouping until I hit this combo. I actually had gone to 26.6 grains and had all the pressure signs including one blown primer. I always err on the light side of loads but in this case........ 
Your gun will decide what it likes. I have a lot of rounds down the barrel before I hit this. Keep at it. Some of the powders I tried were Benchmark, Varget, 4198, 322, blc2, 4895, 3031.
Along the way I discovered how important case length can be and how many thousands a case can grow per each shot. How important consistent crimp pressure, uniform primer pockets and flash holes are. I learned how to do a trigger job on NEF rifles....Highly recommend this!! That will make as big a difference as any load work up!   When reloading EVERYTHING makes a difference
good luck