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Its on all of my magazines and its VERY slight touching. I can only tell by the slightly different sound it makes when I pulled the charging handle when laying prone and dry firing and the mag touches the ground and even then only some of the time. Its not enough to show any marks since it only happens when the mag is pressed in more after its seated or if you press the mag to one side or the other at the base. When the mag is empty I hear a VERY light grating sound. When the mag just hangs there its not touching anything. When its loaded I am wearing hearing protection and hear nothing.
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DevL, if you have no functional problems, I wouldn't worry about it.
The carrier is made of heat treated steel.
Magazine feed lips on the other hand, even those of steel SA-80 mags are of relatively soft material, comparatively speaking.
The feed lips will soon mate(wear down) to the bolt carrier, vs. the other way around. Then one has a perfect fit. From the way you describe I would consider it a break-in issue.
In my view this event would only be an issue requiring action if the bolt carrier prevented from operating properly or was held up on its trip forward and rearward in the reciever. Or is one was having unexplained malfunctions.
I personally would not alter anything, especially not the rifle. As one could easily create a completely unrelated problem that has functional implications.