I've come across a strange situation with a hand loaded 300WM round.
I had new Winchester brass which was FL resized and all other necessary case prep done. They were loaded with 168g Z-Max to a few thou off the lands and i was loading for a ladder test.
I went to chamber one of the rounds and the bolt wouldn't close unless i really forced it, so i didn't fire that round (of course).
I figured that maybe i may have missed a case when sizing and maybe the head space was too long or didn't seat the bullet properly.
When i measured it against a fired case the head space on the unfired round was less than the fired case so that couldn't be the issue.
I then measured the COAL from the ogive against a round that would chamber and the COAL was exactly the same.
This is my first magnum calibre so don't have any experience with belted magnums, but can anyone shed some light on what might be the issue.