Quick detach barrel mounting system

1. A barrel mounting system for removing and attaching a barrel to a receiver of a firearm, comprising:

a barrel nut at least partially receiving a proximal end of the barrel; and

a hand guard extending along at least a portion of the barrel and comprising a cutout defined at an end of the hand guard adjacent the receiver, wherein the hand guard extends along and at least partially encloses at least a portion of the barrel;

wherein at least a portion of the barrel nut is accessible via the cutout of the hand guard sufficient to enable movement of the barrel nut relative to the hand guard to enable detachment or attachment of the barrel to the receiver while the hand guard remains in position relative to the receiver.

2. The barrel mounting system of claim 1 , further comprising at least one mating geometry formed in a peripheral portion of the barrel nut for receiving at least a portion of a tool, wherein the at least one mating geometry in the barrel nut is accessible to the tool via the cutout of the hand guard.

3. The barrel mounting system of claim 2 , wherein the at least one mating geometry comprises a plurality of radially spaced bores or grooves arranged around a circumference of the barrel nut and configured to receive a mating portion of the tool.

4. The barrel mounting system of claim 1 , further comprising at least one radial bore formed in a peripheral portion of the barrel nut and configured for receiving at least a portion of a tool, and wherein a plurality of ridges are formed in an external surface of the barrel nut proximate a rearward end of the barrel nut and the at least one radial bore is disposed in a portion of the barrel nut extending between the plurality of ridges and a forward end of the barrel nut.

5. The barrel mounting system of claim 1 , wherein the barrel nut comprises an axial bore having an internally threaded portion that removably engages an externally threaded portion of a front end of the receiver.

6. The barrel mounting system of claim 5 , wherein the barrel nut comprises an outer circumference, and wherein the cutout of the hand guard is configured to expose at least about a quarter of the outer circumference of the barrel nut on either side of the barrel nut and extends substantially along the barrel nut from adjacent the front end of the receiver for facilitating easy engagement and manipulation of the barrel nut.

7. The barrel mounting system of claim 5 , further comprising a barrel extension disposed at the proximal end of the barrel, the barrel extension comprising an annular collar and a cylinder section extending between a bolt-receiving end and a barrel-receiving end of the barrel extension, the cylinder section at least partially received in the front end of the receiver and having a threaded section therealong adapted to threadably engage the proximal end of the barrel.

8. The barrel mounting system of claim 7 , wherein the axial bore of the barrel nut comprises an intermediate annular shoulder, and wherein the annular collar of the barrel extension is engaged between the intermediate annular shoulder of the barrel nut and the front end of the receiver as the barrel nut is moved toward the receiver.

9. The barrel mounting system of claim 1 , further comprising a barrel bracket disposed at the proximal end of the barrel, the barrel bracket comprising a barrel-receiving bore and a flange, the proximal end of the barrel being received in the barrel-receiving bore so that at least a portion of the barrel bracket is disposed between the barrel nut and the receiver, and wherein the flange of the barrel bracket is at least partially received in a corresponding slot in a chassis of the firearm.

10. The barrel mounting system of claim 1 , wherein the cutout of the hand guard is at least partially defined by a longitudinal edge of the hand guard, a rearward-facing edge of the hand guard, and a portion of the receiver.

11. A method of removing and attaching a barrel to a receiver of a firearm having a hand guard installed over and extending along at least a portion of the barrel so as to at least partially enclose at least a portion of the barrel, the method comprising:

accessing a barrel nut coupling a proximal end of the barrel to a front end of the receiver when the barrel is mounted to the receiver via a cutout defined at an end of the hand guard adjacent the receiver and in a location substantially aligned with the barrel nut;

as the hand guard remains in place installed over the barrel, disengaging the barrel nut from the front end of the receiver by moving the barrel nut relative to the hand guard and the receiver; and

after disengaging the barrel nut from the receiver, withdrawing the barrel from the receiver and the hand guard while the hand guard remains in position relative to the receiver.

12. The method of claim 11 , further comprising:

inserting at least a portion of the barrel and the barrel nut into the hand guard during attachment of the barrel to the receiver so that at least a portion of the proximal end of the barrel is received in the front end of the receiver; and

attaching the barrel to the receiver by accessing the barrel nut via the cutout in the hand guard and moving the barrel nut relative to the hand guard and the receiver to engage the barrel nut and proximal end of the barrel with the front end of the receiver.

13. The method of claim 11 , wherein the accessing the barrel nut comprises inserting a tool at least partially through the cutout in the hand guard, engaging the barrel nut with the tool, and moving the tool in a circumferential direction so as to move the barrel nut relative to the hand guard and the receiver.

14. The method of claim 13 , further comprising disengaging the tool from the barrel nut after at least partially disengaging the barrel nut from the receiver, removing the tool from the cutout of the hand guard, and further moving the barrel nut by hand.

15. The method of claim 13 , wherein the barrel nut comprises at least one mating geometry defined in a peripheral portion of the barrel nut, the tool comprises a corresponding mating geometry, wherein engaging the tool with the barrel nut comprises engaging the mating geometry of the tool with the at least one mating geometry of the barrel nut.

16. The method of claim 11 , wherein the firearm further comprises a barrel extension engaged between the proximal end of the barrel and a front end of the receiver, the barrel extension comprising a cylinder section extending between a bolt-receiving end and a barrel-receiving end of the barrel extension, and an annual collar engaged between an intermediate annular shoulder defined along an axial bore of the barrel nut and the front end of the receiver, and wherein moving the barrel nut comprises unscrewing the barrel nut from the front end of the receiver so as to cause the intermediate annular shoulder of the barrel nut to be moved away from the front end of the receiver so that the annular collar of the barrel extension can be moved away from the front end of the receiver.

17. A firearm, comprising:

a receiver comprising a front end;

a barrel defining a chamber at a proximal end thereof, the proximal end of the barrel being at least partially engaged at the front end of the receiver;

a hand guard being mounted to the receiver at the front end thereof and extending along at least a portion of the barrel, the hand guard having a cutout defined proximate the receiver; and

a barrel nut coupling the proximal end of the barrel to the front end of the receiver, the barrel nut being substantially aligned with the cutout of the hand guard;

wherein the cutout is configured to facilitate access to and engagement of at least a portion of the barrel nut through the hand guard for at least partially moving the barrel nut relative to the receiver and the hand guard sufficient to enable detachment and mounting of the barrel to the receiver of the firearm without removal of the hand guard from the receiver.