Firearm with laterally folding forearm and barrel, and related methods

1. A firearm, comprising:

a receiver;

a forearm pivotally attached to a distal end of the receiver; and

a barrel having a barrel extension, a proximal end of the barrel and barrel extension secured within the forearm such that the barrel and barrel extension are laterally pivotable with the forearm relative to the receiver between a first assembled position and a second folded position without disassembling the forearm from the receiver.

2. The firearm of claim 1 , wherein the forearm, barrel, and barrel extension are slidable relative to the receiver in a longitudinal direction.

3. The firearm of claim 2 , wherein the distal end of the receiver includes a cylindrical surface located and configured to receive the barrel extension therein when the forearm, barrel, and barrel extension are in the first assembled position.

4. The firearm of claim 2 , wherein the forearm includes an elongated slot, the firearm further comprising a pivot pin on the receiver, the pivot pin extending through the elongated slot, wherein the forearm is laterally pivotable relative to the receiver about the pivot pin.

5. The firearm of claim 4 , further comprising a movable locking pin configured to extend through the forearm adjacent to a proximal side of the pivot pin so as to prevent longitudinal movement of the forearm relative to the receiver in the distal, longitudinal direction.

6. The firearm of claim 1 , further comprising a locking mechanism for securing the forearm, barrel, and barrel extension to the receiver in the first assembled position.

7. The firearm of claim 6 , wherein the locking mechanism comprises:

a lever pivotally attached to the forearm;

a hook member pivotally attached to the lever and configured to engage a feature on the receiver;

wherein the hook member may be engaged with the feature on the receiver and the lever moved relative to the forearm to a locking position to generate a compressive force between the barrel extension and the receiver and to secure the forearm, barrel, and barrel extension to the receiver in the first assembled position.

8. The firearm of claim 1 , wherein the barrel extension projects outwardly in the proximal direction from a proximal end of the forearm.

9. The firearm of claim 1 , wherein the firearm is an automatic or semiautomatic rifle, and wherein the barrel includes a gas port extending through the barrel from an inner bore of the barrel, the firearm further comprising:

a bolt carrier group disposed within the receiver;

a gas block mounted to the barrel over the gas port;

a forward gas tube extending between the gas block and the forearm; and

a rear gas tube mounted to the receiver; and

wherein, upon firing a round of ammunition in the firearm, expanding gas within the barrel travels through the gas port in the barrel, through the gas block, through the forward gas tube, and through the rear gas tube and acts upon the bolt carrier group within the receiver so as to cause cycling of the bolt carrier group, cycling of the bolt carrier group resulting in discharge of a spent casing of the round of ammunition and reloading of another round of ammunition into a firing chamber within the barrel.

10. The firearm of claim 9 , wherein one of the forward gas tube and the rear gas tube has a tapered male gas fitting, and wherein the other of the forward gas tube and the rear gas tube has a tapered female gas fitting configured to receive the tapered male gas fitting when the forearm, barrel, and barrel extension are in the first assembled position.

11. The firearm of claim 1 , wherein the proximal end of the barrel is threaded to the barrel extension, and further comprising at least one set screw extending through the forearm and securing the barrel or barrel extension in fixed position relative to the forearm.

12. The firearm of claim 1 , further comprising a handguard secured to the forearm and extending over and around at least a portion of the barrel.

13. The firearm of claim 1 , further comprising a retention mechanism for retaining the forearm, barrel, and barrel extension in fixed position relative to the receiver in the second folded position.

14. A method of using a firearm, comprising:

securing a forearm, barrel, and barrel extension to a receiver in a first assembled position;

firing one or more rounds of ammunition using the firearm;

sliding the forearm, barrel, and barrel extension in a longitudinal direction relative to the receiver so as to remove the barrel extension from the receiver without disassembling the forearm, barrel, and barrel extension from the receiver; and

folding the forearm, barrel, and barrel extension relative to the receiver to a second folded position.

15. The method of claim 14 , wherein folding the forearm, barrel, and barrel extension relative to the receiver to the second folded position comprises folding the forearm, barrel, and barrel extension relative to the receiver in the lateral direction.

16. A method of manufacturing a firearm, comprising:

providing a receiver having a distal end;

providing a barrel having a barrel extension;

securing a proximal end of the barrel and the barrel extension to a forearm; and

attaching the forearm to the distal end of the receiver, such that the barrel and barrel extension are laterally pivotable with the forearm relative to the receiver between a first assembled position and a second folded position.

17. The method of claim 16 , further comprising configuring the forearm, barrel, and barrel extension to be slidable in a longitudinal direction relative to the receiver without disassembling the forearm, barrel, and barrel extension from the receiver.

18. The method of claim 16 , further comprising providing a locking mechanism for securing the forearm, barrel, and barrel extension to the receiver in the first assembled position.

19. The method of claim 16 , further comprising configuring the barrel extension to project outwardly in the proximal direction from a proximal end of the forearm.

20. The method of claim 16 , wherein the firearm is an automatic or semiautomatic rifle, and wherein the barrel includes a gas port extending through the barrel from an inner bore of the barrel, the method further comprising:

disposing a bolt carrier group within the receiver;

mounting a gas block to the barrel over the gas port;

providing a forward gas tube extending between the gas block and the forearm; and

mounting a rear gas tube to the receiver.