Abstract: A take down front pin and take down rear pin designed to simplify the process whereby an upper receiver is engaged with and disengaged from a lower receiver of a firearm. Each of the take down front and rear pins comprises a body having attached to a proximal end thereof a positioning member, wherein, when the pins are properly positioned to engage the upper receiver to the lower receiver, the positioning member protrudes from a main frame of the lower receiver. Furthermore, in addition to the positioning of the positioning member on the firearm such that it protrudes from the lower receiver, thereby making the respective pin easily accessible, the positioning member is also configured to facilitate the manual sliding of the pin to, within, from, and without engaging elements located on the upper and lower receiver of the firearm.

Abstract: A muzzle attachment system for a firearm includes a muzzle attachment having a first engagement means, and a muzzle distal portion including a second engagement means, the second engagement means being complementary with the first engagement means. The first and second engagement means cooperate to releasably secure the muzzle attachment to the muzzle distal portion. The first and second engagement means preferably include complementary coarse threaded engagement portions, an annular grooved surface having a plurality of grooves, a grooved surface engagement mechanism, and first and second position stops that abut to form a gas seal. The muzzle distal portion is preferably a flash suppressor, including at least two elongated ports substantially equally skewed from normal relative to a firing axis of the firearm, and substantially evenly distributed around the circumference of the flash suppressor.