by plant_one » Mon Mar 20, 2017 8:32 pm
ok. so it sure looks like extractor burrs.
pull your BCG and see if you can feel any sharp spots on the extractor claw.
if you cant, try running a q-tip along the edge of it. if it hangs up on anything, a quick buff with some fine (400 grit) sandpaper should smooth things off. be gentle! you're not trying to change anything other than removing machining flaws.
if you're not comfortable with that, you could always contact remington, however their service turnaround times are measured in weeks and sometimes a month or more so you'll have to be willing to part with your upper for some time to get them to correct it.
if you wish to pay a smith, it should be an ez maintenance thing for any respectable smith to do for you.