As long as your rounds plunk your fine.. However I would make sure your not getting bullet set back, I've had that experience with dillion sizing dies, I tossed them.
Win 231 works great, I run 4.8-4.9 1.85oal , 180gr coated bullets.. 10% less for 200gr bullets shoukd get you where you need to be, always chrono though..
All I use are mbx mags. Check the dimensions of the feed lips make sure they are open according to specs.. Definitely go with grams springs and followers..
There is a great vid on YouTube on how to properly adjust the feedlips. Easy fix
I've 401 diameter bullets can be an issue and fact that they are coated.. BB coating tends to be more thicker then other coated bullets.. Check the oal of the bullets that drop in vs the ones that don't, is there an significant variance..
I beting its the 401 diameter bullet.
GL
Anytime!, I personally think Dillion is at the bottom of this list. when I started Loading I used Dillion as well since I own several of there presses but i had nothing but issues with there dies. I.e. sizing issues, de-capping issues