Try a heavier buffer. I was having ejector smears in one of my ARs in .223 no matter the load with heavier projectiles. The pressure builds differently with heavier bullets, so my bolt was unlocking too early while the case was still under enough pressure to have it expanded to the chamber walls. So the bolt was turning while the cases were expanded to the chamber and the ejector was smearing in the head of the brass. Moved to an H3 buffer so I could have the weights to swap around to find what worked better. Turns out the H3 worked wonders. No more smearing on my loads that I push a lil hard. It also helped smooth out the recoil impulse. Seems like the timing issue with the bolt unlocking too early is fixed now. The ejector smearing never happened with the 62 grain and lower stuff, but the 65 grain stuff it would occasionally and over 65 grains it was very regular. Maybe that's why yours is leaving them? Mine did it on light charged loads when using the heavier bullets.