US12753998 - Subsonic firearm cartridge
Firearm cartridges are provided. The firearm cartridge includes a projectile and a cartridge case. The cartridge case includes head, body, shoulder, and neck sections. The cartridge case further includes a case wall. The case wall defines a chamber that extends from the head section to the neck section and has at least a first thickness about the body section and a second thickness about the shoulder section, the second thickness being less than the first thickness. The case wall about the shoulder section defines a hollow volume. The case wall about the neck section engages with the projectile, and the case wall about at least at least a portion of the body section is in contact with the projectile. The chamber is separated into a first chamber portion within the body section and a second chamber portion within the shoulder section by an engagement between the projectile and the wall.