Ok, that means you have gas coming back towards you, your necks and or shoulders are not sealing off. The sides of your cases should have some carbon on them too.They’re coming out of the chamber like this, I was just saying that it doesn’t come off very well in the tumbler. Clean when chambered, black after.
I don’t have the col off hand but it’s not seated long I believe it’s somewhere around 2.885 off the top of my head. And first loading they were fed 210 primers and second I tried cci250s. Neck tension was set with a mandrel on initial firing, and then set back to .001 tension with a Redding type s bushing die. I’ve always set neck tension to .001 in my rifles so not sure if that could be the problem. Also I’m shooting 180vlds with rl26 out of a 26 inch barrelUse a mag primer. Light loads & slow powder may be the cause. Use a faster burn rate of powder. Pressure is low & neck not expanding to seal? Make sure the bullets have enough neck tension. The expander should be .002" smaller than bullet diameter. This will keep the bullet from moving when the primer fires.
*Sorry about the dark text. Copied it from one of my old posts.*
What is your COL? The bullets bearing surface should be in full contact with the neck. If seating the bullet long to get close to the lands/rifling there may not be enough shank of the bullet in the case neck.
There appear to be two strikes on that primer. one that appears normal, and a second inside the first which appears to have been made by a sharper pointed center section of the firing pin.I’ve examined closely and no piercings. I believe what you’re seeing is just a shiny primer with reflections of light above