So...I take my Prohunter out today for its maiden voyage.

All is well, until I start looking at the brass(Hornady factory 225 loads). Visibily noticeable case head expansion about .200 up from the case head.

Measure it to be .0065 from an unfired cartridge. And a noticeably tight fit into the full length sizing die when you get down to the area in question.

You .376 owners out there...are you seeing this too?

Not quite as much as you describe, but my chamber isn't exactly tight either. Still shoots nice groups.
JCN

If you don't like yours loads expansion, do NOT shoot factories in it!!

load down 10% from were you are at.. and try again. if still there, then have it replaced
jeffe