Brass Length on Belted Magnums?

[darkker]

Well, I went ahead and got a Lee Case Trimmer. It used the specific case guage thingy to trim all your brass to the same length. The problem I forsee with the Lee system is it's not adjustable!?! Well I've run into variable case capacities with the 300 win mag pretty fiercely. I'm wondering how consistent the case lengths will be with different brass? I'm assuming different head widths/ internal case dimensions will throw the measurements off since it uses a dowel inserted into the primer pocket as a guage? I hope I haven't wasted my money on this thing!

Lee trims to minimum length, which is irrelevant to usable case capacity. With a bullet seated, the neck isn't part of the capacity the powder has to work with, so if there is more or less doesn't affect it in any meaningful way.