SCP (SOTAR Cam Pin) is a collaboration between Chad Albrecht of School of American Rifle) and Forward Controls Design.
SCP features a machined dimple on one side of the carrier cam pin, so the user can always reinstall the cam pin on the carrier in the same orientation. Cam pin usually wears more heavily on one side, putting the cam pin in one direction, then another randomly creates uneven wear on the cam pin, and it becomes sloppy and loose in the bolt. When the cam pin is installed always facing the same direction, it leaves one side less worn and more intact, this has the effect of better maintaining a tight fit of the cam pin in the bolt, and reduces wear cam pin itself as well as on the cam pin bore on the bolt.
The idea of SCP, or consistently reinstalling the cam pin in the same orientation, isn't so much about saving the cam pin as it is reducing the resulting wear and stress introduced to the bolt. Chad Albrecht is a well respected armorer and instructor, here he explains the benefits of reinstalling the cam pin in the same orientation in this video: Link here
There is a thread on M4Carbine.net on this very issue as well: Link here
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