Straight marks on case heads

[Chickentoast]

300 Win Mag Match, Virgin Lapua brass, H1000, CCI 250's, 208 ELD-M @ 15 off lands. Std R700 bolt, plunger ejector.

3 rounds each from 70-73.5 grains, in 0.5 grain increments, 70 grains is the top row.

Only 3 cases exhibited the issue.
On the far left, in the 1st, 3rd, and 6th rows.

 

[John Glidewell]

good picture of bolt face?

 

[Chickentoast]

Here she is...

 

[John Glidewell]

I can see a line just under the ejector. So I would say it is your bolt face. You can probably feel it if you run your finger nail over it.

 

[Chickentoast]

I still can't see or feel it, but stands to reason it must be there - I'll give the bolt a scrub and see if it either cleans up or becomes more apparent. Thanks!

 

[918v]

Could have been a brass shaving that got stuck between the bolt face and the case head and got ejected.

 

[John Glidewell]

I still can't see or feel it, but stands to reason it must be there - I'll give the bolt a scrub and see if it either cleans up or becomes more apparent. Thanks!

 

[Chickentoast]

That's cool the camera picked it up because I can't see it with the naked eye - different angles and different light, can't see it. I have 74 and 74.5 grains left on virgin brass, then starting 75 grains with 1X brass and continuing up. Figured I'd stop in the 2850 fps range, assuming no pressure, and move into tenths of powder to find the sweet spot.

 

[Steel head]

Could have been a brass shaving that got stuck between the bolt face and the case head and got ejected.

This