If you live in Massachusetts, this video is more than mere esoterica. Thanks to Bay State legislature’s infinite wisdom, residents can own and carry standard capacity GLOCK magazines only if they were manufactured “pre-ban” (September 1994). Otherwise, it’s ten rounds for you, boyo. How do they know? They know. How do you know? You watch this video. On a personal note, I’d like to have a quarter of the firearms knowledge residing in the noggins of TTAG’s Armed Intelligentsia. I don’t. Thank you for sharing it with us in the comments section, helping keep this site true to its name.