AR15 - Damaged ejection port via sanding?

[shadow9]

Picked up a new AR15 "Mil-Spec" upper recently, and found the dust-cover hard to close compared to a "non-mil-spec" upper.

So, I took some 600grit sandpaper and a toothpick to try to "wear" up the notch that the cover pin snaps on, and managed to take the black dye off of of the metal, and about 50-60 passes on the divot/notch that the dust-cover retaining pin interacts with.

Pics later, but it seems the black anodizing is missing, the metal is a bit shiny, but the cover is only marginally easier to close.

My concern is that I now will have excess wear to the dust-cover notch, as I read that once you get through 0.02" of Hard Anodizing (per Mil-Spec), it exposes the softer aluminum underneath, regardless of the aluminum oxide that forms on bare aluminum....any input?

 

[rcmodel]

I would have suggested you just grease it and use it until it broke in.

Too late now.

A dab of grease would still be a good idea though.
And make sure the plunger & spring are operating freely.

rc

 

[USAF_Vet]

The dust cover on my newest upper is very tight to snap shut, but pops open as it should without any difficulty when operating the bolt.

There may be some packing/ preservative grease in the spring under the detente ball. There was on mine. Use some non-chlorinated brake cleaner or another degreaser that won't strip the finish off the steel and clean the dust cover. A dab of lithium grease on the ball and spring after cleaning should have freed it up and been GTG.

I'd not have recommended sanding the upper receiver. Dust cover assemblies run about $15 on Amazon. Worst case, buy another dust cover and see if it fits better.

But, as RC said, too late now.

 

[rbernie]

My concern is that I now will have excess wear to the dust-cover notch, as I read that once you get through 0.02" of Hard Anodizing (per Mil-Spec), it exposes the softer aluminum underneath, regardless of the aluminum oxide that forms on bare aluminum....any input?

Worst case scenario? The dust cover eventually stops snapping shut.

In other words, it's not that big of a deal. And in the end, hopefully you've learned a lesson about not trying permanent modifications before trying non-permanent ones.