Thanks for the replies chaps.

Talking to a few guys at the club yesterday it seems pretty common, though it is the first time I have experienced it.

One thing that still does worry me is the bullet won't have full contact with the entire length of the neck, it'll just be seated a partial way down. Might not be such an issue but I bet it'll leave a visible band on the outside of the cartridge, and this I haven't seen before.

Cheers
Greg