United States v. DeBorba, decided on June 3, is the latest Ninth Circuit decision that seeks to exclude firearm parts from protection in the reference to the "arms" that the people have a right to keep and bear. The court held that "'optional accessories' to firearms—such as gun slings, scopes, and, importantly, silencers—fall outside of the Second Amendment's plain text because they are 'accoutrements' and not arms." The test for whether an object is included in "arms" is supposedly based on whether it "is necessary to the ordinary operation of the weapon." "Ordinary" means anything you want it to mean.
That conclusion derives from the Ninth Circuit's 2025 en banc decision in Duncan v. Becerra, which claimed that a ten (or fewer) round magazine is necessary to operate a semiautomatic firearm and is thus protected, but a magazine that holds over ten is not necessary and therefore has no protection. For the basis for this illogic, see my post here.
It's no surprise that the DeBorba court applied that "test" to the much-derided suppressors, but gun slings and scopes? Perhaps the court is laying the groundwork for the California legislature to ban "assault slings" and "assassin scopes." After all, slings may be used in the standing (off-hand) position to shoot more accurately, as they often are at shooting matches. But that could make spray firing more accurate as well. And despite their use in hunting, scopes are inherently "military-style" as depicted in the movie American Sniper, making them adaptable to political assassinations.