Abstract: Firearms having threaded barrels with hidden threads. The barrel has a threaded portion disposed within the slide of the firearm when the firearm is in battery so that the muzzle end of the barrel is aligned with the muzzle end of the slide. The barrel is configured to couple with a barrel attachment, such as a thread protector, such that the coupling portion of the barrel attachment is disposed within the slide of the firearm when the firearm is in battery.

Abstract: Firearms having threaded barrels with hidden threads. The barrel has a threaded portion disposed within the slide of the firearm when the firearm is in battery so that the muzzle end of the barrel is aligned with the muzzle end of the slide. The barrel is configured to couple with a barrel attachment, such as a thread protector, such that the coupling portion of the barrel attachment is disposed within the slide of the firearm when the firearm is in battery.

Abstract: A magwell adapter is provided for use with a firearm. The firearm can include a firearm frame having a barrel section and a grip section. The grip section of the firearm can include a sear spring alignment plate, a magazine well, a sear spring, and a main spring cavity. The magwell adapter can be slidably coupled to the bottom end of the grip section of the firearm or coupled in another manner. The magwell adapter can include an aperture for receiving a tab of and holding the sear spring in place within the grip section. The magwell adapter can also include one or more pin receiving apertures adjacent to a rear end of the adapter. The pin receiving apertures can be configured to receive a mainspring housing pin to couple the mainspring housing to the magwell adapter when the mainspring housing is inserted into the grip section of the firearm.

Abstract: A sight mounting system can include an accessory mounting plate that can be removably coupled to the firearm. The accessory mounting plate can include a mounting slot along a bottom side and an accessory mounting surface along the top side for receiving a removable sight thereon. The accessory mounting surface can include one or more projections that extend up from the mounting surface and one or more threaded apertures extending into the mounting surface for coupling a sight to the plate. The plate can also include an alignment pin cavity extending from one side to the other of the plate and another threaded aperture extending into the top side of the plate. The threaded aperture and the pin cavity can both be in fluid communication with the mounting slot. A pin can be inserted into the pin cavity and pushed into place by a screw through the threaded aperture.