Have never even heard of this. Hoping for some guidance from the forum members.

I have a bunch of Norma brass for 300 Win Mag. Got it shooting under 1" with 180 grain Hornady CX and RL 22. FN Mauser action, which plays a part here. Noticed, however that when chambering the case I encounter a spot where the bolt gets a little hung up. And the front edge of the rim gets a little chewed up.

Turns out that "spot" has to do with the groove on the case getting slightly stuck entering the extractor groove on the CRF bolt as the bolt is pushed forward and the case moves up into the bolt face.

Took it to a gunsmith and we measured several types of cases. Turns out the groove on the Norma cases are about 5-8 thousandths bigger than the cases we measured - Remington, Hornady, Federal were all smaller in diameter than the Norma case.

I can push briskly and get the bolt to close, and it shoots well. Just surprised that there would be a difference in the size (diameter) of the groove on the cases, and that it would even make a difference!

Anyone ever encounter this? Is it just a run of Norma cases that are bigger in this dimension or are all 300 WM Norma cases that way?

I was using handloads in Norma brass today in my Sako M85 Finlite in .300 Win. They feed very smoothly from the magazine into the chamber in my rifle. They seem just like the Winchester brass I have used. Maybe your rifle just does not like the Norma brass.

Check to see if you have a chamfer on the bottom edge of the extractor blade. Stoning a good chamfer here helps smoothen the ride of cartridges out of the mag and up onto the bolt face.
When I received my Mauser 404 it really hung up on the feed and scratched hell out of the cases as they scrapped along on the side rails due to the case head not moving freely up onto the bolt face. A little light stoning to the extractor blade lower lip and all was solved. The 404 feeds like a hot knife thru butter just with that one simple fix.

(( Turns out the groove on the Norma cases are about 5-8 thousandths bigger than the cases we measured - Remington, Hornady, Federal were all smaller in diameter than the Norma case. ))

Yep. I have noticed that. Was having an issue with an M70 action similar to what Eagle describes above which caused me to compare some rim thickness differences. In my case comparing only Hornady to Norma and the Norma is thicker.

Eagle 27 that is what my gunsmith will be doing, though ever so lightly!

Thanks for the feedback, gents.

Probably one of those factors that would favor a push feed over controlled round feed. This used to be a 375 Wby, and as a dangerous game rifle, personally I would have a slight preference for the CRF. It’s now a 300 Win and not in that category.

.475 minus .020. Is the SAAMI spec groove. What did yours measure?

0.4675 as close as I can tell.

Then it is fully within SAAMI specification, in which case I would be checking my extractor. Brass is fine.

See here. This also on an FN:

As per my earlier post this chamfer stoned on the bottom edge of the extractor blade on my Oberndorf Mauser Sporter completely cured absolute shit feed from magazine of the big 404J rounds. Rifle had been opened up from 10.75x68 to 404J and obviously not used in that guise until I purchased it. Needed the extractor done and a new higher front sight blade to bring POI down for the 404J cartridge.

Great photo - thank you! Makes it very clear.