A paintball gun conveniently assembled in the present invention has a through hole formed in a back of a grip and communicated with a chamber of the grip; a set bolt having an engagement groove and being extended into the through hole, protruded into the chamber and pressed against a magnetic-attraction plate; a setscrew hole formed in one sidewall of the grip and communicated with the through hole for being screwed with a setscrew, whereby the set bolt designed with different length can be extended into the through hole to push the magnetic-attraction plate, and then screwed with the setscrew tightly so that a push rod of the magnetic-attraction plate can push a locking member to adjust the displacement height of the locking member for different types of the gun bodies, thus a single grip is suited for being conveniently and quickly assembled with a gun body of different style.

Disclosed herein is a modular, replacement chassis stock system for an existing firearm's operating mechanism possessing a simple design and incorporating durable, commercially available components. The system comprises a chassis assembly with up to three integral mounting rails, a top rail, a replacement operating rod guide, a telescoping buttstock assembly, and a buttstock/grip mount assembly. The present invention may be used to replace the standard stock of an M-14 rifle (or copies thereof, such as the Springfield Armory M1A) such that the barrel is held in perfect alignment with up to five Mil Std 1913 pattern mounting rails. The telescoping buttstock assembly is adjustable in length via the use of a thumb lever release and includes an adjustable cheek-rest, an optionally adjustable buttpad, and a pistol grip. Auxiliary devices may be attached to the chassis stock system via the buttstock/grip mount assembly located above the pistol grip. The chassis stock system is secured at the rear of the barreled action by the installation of the trigger assembly and at the front by attaching it to the replacement operating rod guide.

A firearm interface for a buttstock and pistol grip that provides a means to attach a pistol grip or a buttstock assembly to a firearm, and shotguns in particular. It can be used for either modality individually or both in combination. It allows the utilization of an M16/M4 style pistol grip and the adjustable, as well as the fixed buttstocks of M4/M16 style rifles and carbines. The buttstock and pistol grip interface confers the ability to configure the firearm to different requirements and to the ergonometric needs of diverse individuals. By facilitating the use of M4/M16 style receiver extensions and M16/M4 style pistol grips the buttstock and pistol grip interface brings a vast array of options to the firearms to which it is affixed. For those individuals with military experience the use of M16/M4 style components imparts a degree of familiarity and utility.

A stock connector allows for secure attachment of various stocks to firearm receivers. The stocks can be changed out easily and quickly in the field, without the use of specialized tools.

The present invention is a modular stock system for rifles. The system replaces the rifle's buffer tube with a modified one containing a mount for a constant cheek weld and a rail track for adjustment. A hind portion then mounts on the replacement buffer tube. The hind portion is interchangeable depending on the user's needs. Various configurations of the hind portion are discussed, including adjustable stocks, fixed stocks, and specialized stocks. The hind portion may be made even further modular by the addition of rail system.