As you are clearly not familiar with the parts or function of your carbine, I suggest a recalibration before asking about a "known problem".. inferring issues with LMT's products.
Cam pin is a bearing surface, when metal on metal force is transmitted, it will show surface wear.
Surfaces wear spots are where one should grease/lube
Is there a functional problem?
Piston MRP's should have a H2 buffer and a reputable recoil spring. How is your lower configured?
If a DI MRP barrel is purchased, a regular bolt group is used.





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