Mag fed loads not grouping well

[lazyengineer]

I will say, I thought I experienced this sometimes in my 6.5 Creedmoor AR10. I recall having some issues with some of my extractor tension for a while, and had to single load each shot for a few strings. There was vertical stringing with that particular ammo, and it went away went I switched to manually loading every shot; and I didn't know what to think of it. Most explanations on the topic, you'd think would show up as overall general group dispersion, not tight windage but large verticle dispersion. I figured it had to do with recoil moving the gun back shot to shot, which cased different recoil behavior the next shot, which affected it's elevation of impact. But who knows, I'm curious what others say.