Critical Machining Operations Test

Definition

The standard ATF applied before 2022, examining whether the key manufacturing steps needed to create a frame or receiver's functional areas — specifically the holes and material removals that allow firing components to be installed — had already been performed. If those critical operations were done, the item was regulated; if they remained undone, it was not.

Examples

• •Under this test, an AR-15 lower receiver was not regulated as a machine gun receiver because the single 'third hole' distinguishing a semi-automatic receiver from a machine gun receiver had not yet been drilled

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