Brass looks funny

[bfk4lyfe]

Can someone explain what’s going on here with the obvious differences in brass discoloration after being fired, and if it’s anything to be concerned about:

I have once fired (in my rifle) Prime 223 brass, resized with a Redding non bushing die, bumped .004. These reloads are 26.0 through 27.5 gr of CFE223 with a Hornady 53 gr vmax. Rifle is a BCM 16” AR, their SS410 barrel. The shiny piece is always the last case and always ejects to 5:30, while the other ones eject closer to 1:30.

 

[HumpHammrr]

What I'm seeing is the discoloration from powder gasses that escapes back over the front part of the case in the micro-second between bullet exiting the case mouth and before the case expands to seal the chamber. Not sure why the last case is cleaner. As for the ejection, the #1 through next to last has full bolt travel effecting the ejection pattern. The last case fired has the bolt being caught by the bolt catch.

 

[Snuby642]

The last round does not have any upward pressure on the bcg.
It's going to eject different and a lot of time is a flier out of my groups.

I get way dirtier brass running suppressed till I put in an agb.

 

[bfk4lyfe]

Do you think the bottom of the case isn’t covered in gas because it didn’t get resized in the process so it’s already sealed to the chamber?

 

[Snuby642]

Don't know.
You said .004 bump and mine run .0035 to .004.

Your brass looks pretty normal with the 5th round exception. I have not noticed that in my gas guns, 223, 300blk and 6.5g.

Are you getting normal bolt hold open?

 

[bfk4lyfe]

Yeah it ran fine.

 

[Snuby642]

I'll look at my brass tomorrow but close to the same I think.

I'm testing cfe223 26.5 looked good but got side tracked and not got to 27.5 yet suppressor got loose and blew my test groops.

What load was best?

 

[bfk4lyfe]

They were all not very good, best was maybe an inch, which was the 27.0 load. I’ll try to work up to 28.0 if it’s safe. To be honest I’m just killing some time and using up random components I have lying around, corona and what not.

 

[Snuby642]

Just a random reload not sure when fired. Lighting not good enough to show slightly shinier first 1/4 inch from base.

From 27.5 to 28gr you might get compressed. I think would be close with 55g bullets loaded to book coal.

I may try fudging another 020 thousand on my length if cannelure and pmags allow.

On my 300bkk cfeblk loads with subs the bullet is sitting right on top but not compressed and runs 1 moa.
Not bad for a 220g sub. Oh thats in the bolt gun not the sbr.

Have not seen any 223cfe loads compressed in books or online.

I really dont think you have a problem.

Maybe @spife7980 would take a look he is good and helped me a lot.

That last clean round is still puzzling.