Ok, did some testing with a suspect cartridge (RWS headstamp), and a known good cartridge (LC headstamp). I used two Amax bullets that measured as close to identical as possible in diameter and weight.
SWC:
Length before resizing 1.3570
resized using Hornady FL die
neck outside diameter .3335
chambered and ejected OK
Loaded with Amax 308 208gr bullet
neck outside diameter now .3370
Sharpie applied to case neck, shoulder, and bullet ogive
Jammed on chambering, rub marks on bottom of neck and on shoulder
LC:
Length before resizing 1.3575
resized using Hornady FL die
neck outside diameter .3290
chambered and ejected OK
Loaded with Amax 308 208gr bullet
neck outside diameter now .3310
Sharpie applied to case neck, shoulder, and bullet ogive
Chambered and ejected with no issues, hair thin rub line where neck meets shoulder
Pictures:
SWC:
LC:
The differences in diameters (~.0050) corroborate with the documented case differences in the link
chrismartin posted. I'm guessing that the thick necks are causing my jams. I'm going to reload some LC brass only and test them in the next couple of days.