US Patent 10145648 Anti-slip handguard assembly

A handguard assembly includes a handguard and a key. The handguard includes a first ear with a first ear inner surface and a second ear with a second ear inner surface that cooperate to define a slot that extends in a longitudinal direction. The key is received in the handguard and includes a main body with an interior side and an exterior side that face in opposite directions from one another so as to define a main body depth and a first projection extending from the interior side of the main body so as to define a first projection depth. The first projection includes a first projection contact face that contacts the second ear inner surface when at least one fastener compresses the slot so as to prevent overtightening of the handguard.