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In California, flash suppressors are generally restricted on semi-automatic rifles with certain features that are considered "assault weapons". Specifically, a semi-automatic rifle with a detachable magazine and a flash suppressor (or certain other features like a threaded barrel capable of accepting one) is classified as an assault weapon. However, flash suppressors can be legally used on firearms that are not classified as assault weapons, such as those with fixed magazines or those that don't have other prohibited features.