At least that is what I thought. It looks like a chip is missing from it but I now see that they were made that way on purpose. Why would Marlin do that? It's not very comforting when you can see the back of the brass when the lever is fully closed! I was on a whitetail hunt in Manitoba and I noticed it. I don't know how I failed to see it before but I thought a piece had chipped off while target shooting and that the gun was unsafe. So I went to a gunstore and ended up buying a used Winchester 70 300 mag Supergrade. I hunted with that for the rest of the trip. (Really nice gun!). I bought it for nothing as it turns out but I ended up wasting a day.
I'm glad that there was no problem because I really love that Marlin. It's the only true MOA lever gun I have ever seen.

You should write Marlin and thank them for giving you the excuse to buy that Supergrade! My Marlin is a MOA gun too (M1895) and continues to blow my mind that an out of the box levergun can shoot so well.

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The accuracy of this gun surprises a lot of people who see it. My dad had an old Marlin from the 1960's in 32 special. It shot 2.5" groups and that is what was expected from that era. He is astounded by the accuracy that this gun displays. My Marlin regularly shoots better groups than most people's bolt guns. Marlin really did a great job on this gun!