Small Base Sizing Die Needed?

[Wannashootit]

Mostly a bolt-gun guy, couple of AR's but haven't run into this particular issue before.
AR barrel chambered in 6.5 Grendel.

Gun runs factory Hornady ammo (123's) flawlessly.

With Hornady headspace comparator, bumping the shoulder waaaay further than either factory Hornady ammo out of the box, and fired brass and still can't get the bolt into battery.

Checked diameter at the base of the cartridge, Hornady factory is remarkably consistent at .4374 at the base.
Sizing die (FL, Hornady) is giving me .439-4397 regardless of amount of bump used.

I'd built a 6.5 G years ago when AA first introduced it and didn't have this issue with the same dies, so there's obviously a small variation in the chambers.

Pretty sure I need a small base die here, just want to be sure there's nothing I'm missing...

 

[TheOfficeT-Rex]

Something doesn't add up - the SAAMI drawing for 6.5 Grendel shows .4410 at the base for maximum case size.

If you plunk test, can you see where it hangs up in the chamber?

 

[Wannashootit]

Yeah- looked at the SAAMI drawing after I posted...
I don't get it, either. I had a bunch of old, unfired rounds from the previous one I had, those will not chamber either.

I'd suspect the chamber, but given factory runs fine doesn't seem to be a possibility, unless for some reason it is under spec just enough to cause the problem.

CBI barrel. Should I cast the chamber?

 

[TheOfficeT-Rex]

Casting can't hurt. I'd try to plunk just a resized brass first, see if maybe the bullet is causing the hang up.

For reference, here are the red and yellow book pages - they have slightly different case dimensions, but should give you something else to work off of for measurements.

 

[Wannashootit]

Thanks-
Think I figured out the issue- the extractor is STIFF.
I mean, really stiff- "pushing" the bolt as hard as I could wouldn't get it into battery -but when I slam the palm of my hand into the back of the bolt, it will go into battery.
Guess I'm just not used to that much resistance from an extractor.

 

[Mad_Charlie]

I had a bolt like that, I wound up buying "extra power" extractor springs from Brownell's and removing all the rubber and the stock spring from underneath the extractor. I also "de-fanged" and polished the leading surface of the extractor. The little Grendel has run like a top ever since.