Modular rimfire handgun

A firearm comprising:

• a receiver;
• a grip extending from the receiver;
• a barrel coupled to the receiver;
• a bolt assembly housed within the receiver, the bolt assembly comprising a locking block and a carrier, wherein the locking block is configured to engage a locking surface of the receiver when the bolt assembly is in a locked position, and wherein an angled interface between the locking block and the carrier is configured to cause the locking block to disengage from the locking surface when the carrier moves rearward;
• and
• a charging handle coupled to the bolt assembly and connected to the carrier via a charge handle link, wherein rearward movement of the charging handle causes the carrier to move rearward and disengage the locking block from the locking surface.

A magazine for a firearm, the magazine comprising:

• an injection molded magazine body configured to retain rimfire cartridges in an angled orientation;
• a stamped backer plate attached to the injection molded magazine body, wherein the injection molded magazine body comprises a plurality of raised posts and the stamped backer plate comprises a plurality of holes configured to interface with the plurality of raised posts to secure the stamped backer plate to the injection molded magazine body;
• and
• a follower positioned within the injection molded magazine body, the follower configured to pivot to support the angled rimfire cartridges.