So I have a new Seekins SP10 6.5 Creedmoor that I'm doing some load developing. I'm trying to get the most I can long range with this gun. I decided to remove the expander out of the FL die and use a 21st century NT26 turning mandrel arbor after full length sizing to make the ID of the cases more uniform without the hassle of neck turning. I'm having good luck developing a load and have found a few that I like. With my first sizing of new cases I threaded the die all the way in till it touched the shell holder and sized my brass as I didn't know the headspace of fired brass for this rifle. After shooting the brass I checked the size of the brass with the hornady comparator with the 375 bushing and it measured 1.556. So I put that brass through the press with the die screwed all the way in to touch the shell holder so I could back off the die. To my surprise, the brass came out to 1.557 so it actual grew. Tried it a few times and the same result every time. I put the expander ball back in the FL die and with that installed it does push the brass back. I also followed up with the turning mandrel to see if that would push the brass back a bit with no luck. So what are you guys doing this to remedy the problem? Is this something I should be concerned with? I've shot rounds that I've sized this way with no problems functioning. For now I'm just using the die screwed in all the way to the shell holder. It just concerns me as you're supposed to push the brass back a bit for sizing and I'm not. Thoughts and opinions would be appreciated as I'm thinking of going back to the expander ball. I am getting good accuracy with the turning mandrel method without the expander installed. Seating bullet pressure has also been very consistent. Thoughts and opinions would be appreciated.