If you're not turning your necks, your neck tension can vary due to different case neck thickness, when using the bushings. An easy and fairly inexpensive way to get more equal tension, from case to case, is using an expander mandrel.
I have had good results using a bushing, .003" under caliber to size the neck down, then expanding the neck up .001" using a .002" under caliber mandrel.
Another option is using a FL die with no expander. It will resize your case dimensions and take your neck ID down .003-.004. You can then run a .002" under caliber mandrel to set your neck tension. This is my first choice.
K&M has the die and numerous choices of mandrels and they work fine. I also use a die and mandrels made from pin gauges. Kenny Porter makes this collet type die.