It looks like a late style rear sight.
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Several months ago I was gifted(?) a Marlin 60. Circa 2000 with 22" barrel. Love it. My first 22 rifle. Being in my mid 60's I really curse myself for this oversight now.
My question is what rear sight is this.
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If I remember right, they are Marbles sights...
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The Model 25N Marlins that I bought for my 2 sons both had that rear sight as original from the factory. Not shown as that way on Numrich's schematic, but that's absolutely what they came with. I replaced them with the typical "better" Marlin rear sight with stepped slide and the flip up-down blade. (Not the cheaper sight where the blade is just a bent extension.) I then replaced the blade with this flip up-down "ghost ring" and a taller front sight to match it.
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