SmallCaliberCentral

I've been waiting a few weeks now for the weather to improve, to try out my new 204r pac-nor barrel. Today i fired 5 rounds. The fired cases measure .373 dia. just in front of the extracter groove. when i take a measurement .375 along the case from the back, the dia. has increased to .3765. Surely this can't be right? Regards,Ken.

Ken

Most likely its your brass thats wrong, not the chamber. Shooting Winchester brass by chance?
Check the Sierra data with cartridge dimensions at the top of the page. Case dimension above web is stated as .376"

Winchester brass I have measures .372" above extractor groove. Measures .376+ past the web where it bulges. This is in what I would call a "semi custom" chamber much like what Pac-Nor might have.

In comparison Nosler brass fired in my big ol sloppy Savage chamber measures .375 above the extractor groove. Blows out to .378 farther up.

Your chamber specs seem OK to me. It is a "semi custom" chamber after all. Just big enough to ensure factory ammo will chamber.
Either way it should'nt matter much. If you necksize it'll stay where it is anyway. If you FL size your die probably won't squeeze it all the way back to where it started from out of the factory either.

jo, I should have said that is Hornady factory ammo 32g. Also i ommited to say that i bought the barrel as a blank and my 'smith chambered it,with what i presume a sammi spec reamer. Anyway, you've put my mind at rest. Thanks very much. Regards,Ken.

jo191145 and Rick, Thanks, Ken.