check shoulder dia. also take a magic marker and darken completely one of the cartridges in question including the bullet, then re-insert and extract....look for bright marks on the case or bullet.
I'd check the shoulder CAREFULLY as bullet seating can expand it slightly leading to non-chambering
can i chamber the empty round to eliminate the brass before i load?
If it's a bulge from the crimp, it will chamber fine before you seat the bullet and crimp. It's not the brass, it's the process that's hanging up.
I'm cheap, and the last few that I did that (I backed off my crimp when I discovered why they wouldn't chamber) I pulled the bullet, resized and reloaded.
i did notice that the rim had some rough cuts in it all 4 rounds
a bent or upset rim WILL make it difficult/impossible to close the bolt...the dies and shellholders are set to return brass to the nominal size...but the bolt is a SOLID surface that catches all the offset. take a round that wont chamber and a file and CAREFULLY dress the base of the cartridge flat and try it again...also try chambering a resized round with no powder or bullet.
misc brass once fired not from my rifle