223 - Help explaining these pressure signs

[dsmhero]

This is my first load up of 223 but I am getting some odd pressure signs when I believe there shouldn't be.

Data:
RRA LAR-15
16" barrel
Cheap 224 55grain fmj bullets I bought at a gunshow
COAL - 2.235
Accurate 2230
6 1/2 primers
Once shot mil brass

So I did a load up of 22grains - 24grains by 0.5grain increments. Outside temp was 85F.

At 23grains I had one pierced primer out of 10 rounds.


Back row is 23.5 and front is 24 grains


I was getting extractor marks at 23.5


Here is the chrono data:
22grains - Average 2686 fps with sd 70 fps
22.5 grains - Average 2708 fps with sd 57 fps
23 grains - Average 2760 fps with sd 41 fps
23.5 grains - Average 2779 fps with sd 54 fps
24 grains - Average 2872 fps with sd 44 fps

Any idea on what is going on and if I am actually pushing this charge too far?

 

[dsmhero]

Problem solved, looks like the 6 1/2 primers are NOT to be used with high pressure cartridges.

 

[FearNoWind]

Here is the chrono data:
22grains - Average 2686 fps with sd 70 fps
22.5 grains - Average 2708 fps with sd 57 fps
23 grains - Average 2760 fps with sd 41 fps
23.5 grains - Average 2779 fps with sd 54 fps
24 grains - Average 2872 fps with sd 44 fps

Always good to know everything worked out fine.
Regarding your data, what you have listed as SD appears to actually be ES.

 

[dsmhero]

Always good to know everything worked out fine.
Regarding your data, what you have listed as SD appears to actually be ES.

No, my extreme spread is in the low 100 fps. Not sure as to why.

 

[MagnumManiac]

You need to change out your primer for the 7 1/2, the 6 1/2 is too soft and will pierce readily. Don't worry we've all made that mistake before. I did in my 17 Rem, first shot, gas in the face, didn't know why until I looked at the base of the fired case. Switched back to 7 1/2, problem fixed.

Cheers.
gun)

 

[dsmhero]

You need to change out your primer for the 7 1/2, the 6 1/2 is too soft and will pierce readily. Don't worry we've all made that mistake before. I did in my 17 Rem, first shot, gas in the face, didn't know why until I looked at the base of the fired case. Switched back to 7 1/2, problem fixed.

Cheers.
gun)

Thanks for the reply. Looks like they will be used in my 9mm now. At least they wont go to waste.