Help identifying a cartridge case.

[Darrell]

I thought I had a bunch of 7.62 x 39 cases. I don't reload this caliber, so after identifying one case I just visually put a bunch in the same pile. Wrong answer!  Almost all the cases are physically smaller than the 7.62 x 39, but the head stamp doesn't identify caliber, only the LC mark.  What do I have here?   Thanks!

[Alleycat72]

300 blackout/300 Whisper 

[Thursty]

Agreed. 

[Garufa]

More specifically, .300 Blackout created from Lake City 5.56 NATO brass.

[Alleycat72]

20 minutes ago, Garufa said:

More specifically, .300 Blackout created from Lake City 5.56 NATO brass.

And was a subsonic load.

[Garufa]

2 hours ago, Alleycat72 said:

And was a subsonic load.

How can you tell that?

[Alleycat72]

Just now, Garufa said:

How can you tell that?

The primers. Subs will cause that overly round fired primer.

[Darrell]

2 hours ago, Alleycat72 said:

300 blackout/300 Whisper 

Thank you all! Just shows to go ya that a fellow can learn something everyday.