I am currently running a Aero Precision M16A4 build with a 20 inch barrel and rifle length gas system/buffer. The other day when I returned from the range I noticed some wear marks that I hadn't noticed before. It looks like the Carrier Gas Key is dragging on the upper right inside of my receiver above the rails where the bolt runs. The rifle has about 800 rounds through it and is constantly cleaned and well oiled after each outing. Can anyone tell me what's going on here as I cannot seem to find any info on the subject. I contacted Aero precision on Instagram and sent them photos they told me the bolt can bounce around a lil bit inside the upper and that can cause the wear pattern im seeing they told me keep shooting the rifle and it will smooth out over time. I wanted to post here to see if anyone has seen this before and can tell me what's going on with my upper receiver and bolt

I see nothing more than a little finish wear. If it's worked well for almost a thousand rounds to this point, I would say you aren't looking at anything out of the ordinary.

No problem.