Drum magazine assembly and methods
A magazine assembly for a firearm and a related method are disclosed. The assembly has a magazine housing defining a track, and a follower assembly. The magazine housing is configured to constrain a cartridge as the cartridge is moved within the magazine assembly such that majority of a proximal surface area of the cartridge does not contact the magazine housing, and a distal tip of the cartridge does not contact the magazine housing.
1. A drum magazine assembly for a firearm, the drum magazine assembly comprising:
a drum assembly comprising a wheel;
a spindle assembly;
a feed tower assembly; and
an advancing mechanism to advance the wheel such that one or more cartridges of ammunition may be loaded after advancing the wheel, the advancing mechanism comprising an arm, a pawl, and a lever, wherein: the arm is configured to pivot about a first pivot axis to drive the pawl about the first pivot axis, the first pivot axis defined by the spindle assembly;
the pawl is configured to pivot about a second pivot axis between a free position and an engage position, the second pivot axis defined by a distal section of the arm;
the pawl is further configured to selectively engage the wheel when the pawl is in the engage position;
the lever is configured to pivot the pawl about the second pivot axis;
the lever is further configured to move relative to the second pivot axis between a closed position and an open position.
2. The drum magazine assembly of claim 1 , wherein:
the lever is configured to bias the pawl towards the free position when the lever is in the closed position; and the lever is configured to bias the pawl towards the engage position when the lever is in the open position.
3. The drum magazine assembly of claim 1 , wherein:
the lever comprises a pawl pin and spring to bias the pawl towards the free position when the lever is in the closed position, and to bias the pawl towards the engage position when the lever is in an open position.
4. The drum magazine assembly of claim 1 , wherein:
the lever comprises an advancement lock to prevent the pawl from engaging the wheel when the lever is in the closed position.
5. The drum magazine assembly of claim 4 , wherein:
the advancement lock comprises configured clearance groove to provide a clearance to selectively allow advancement of the wheel when the lever is in the open position.
6. The drum magazine assembly of claim 5 , wherein:
the lever comprises a lever lock configured to prevent the lever from being moved from the closed position to the open position when the drum magazine assembly is installed in a weapon.
7. The drum magazine assembly of claim 1 , further comprising:
an arm return spring configured to return the arm to a start position after an advancing motion.
8. The drum magazine assembly of claim 1 , wherein:
the advancing mechanism is configured to advance the wheel such that two or more cartridges of ammunition may be loaded after advancing the wheel.
9. An advancing mechanism for a drum magazine assembly, the advancing mechanism comprising an arm, a pawl, and a lever, wherein:
the advancing mechanism is configured to advance a wheel of a drum magazine assembly such at least one cartridge of ammunition may be loaded after advancing the wheel;
the arm is configured to pivot about a first pivot axis, the first pivot axis defined by a spindle of a drum magazine assembly, the arm further configured to drive the pawl;
the pawl is configured to pivot about a second pivot axis between a free position and an engage position, the second pivot axis defined by a distal section of the arm, to selectively engage a wheel of a drum magazine assembly when the pawl is in the engage position; the lever is configured to pivot the pawl about the second pivot axis, the lever further configured to move relative to the second pivot axis between a closed position and an open position.
10. The advancing mechanism of claim 9 , wherein:
the lever biases the pawl towards the free position when the lever is in the closed position; and
the lever biases the pawl towards the engage position when the lever is in an open position.
11. The advancing mechanism of claim 10 , wherein:
the lever comprises a pawl pin and spring to bias the pawl towards the free position when the lever is in the closed position, and to bias the pawl towards the engage position when the lever is in an open position.
12. The advancing mechanism of claim 9 , wherein:
the advancing mechanism is configured to advance a wheel of a drum magazine assembly such that two or more cartridges of ammunition may be loaded after advancing the wheel.
13. The advancing mechanism of claim 9 , wherein:
the lever comprises an advancement lock to prevent the lever from driving the wheel when the lever is in the closed position.
14. The advancing mechanism of claim 13 , wherein:
the advancement lock comprises a clearance groove to provide a clearance for allowing the lever to advance when the lever is in the open position.
15. The advancing mechanism of claim 9 , wherein:
the lever comprises a lever lock configured to prevent the lever from being moved from the closed position to the open position when the advancing mechanism is installed in a drum magazine assembly installed in a weapon.
16. The advancing mechanism of claim 9 , wherein:
the advancing mechanism is configured to advance a wheel having teeth arranged about a distal circumference of the wheel.
17. The advancing mechanism of claim 16 , further comprising:
an arm return spring configured to return the arm to a start position after a advancing motion in the drum magazine assembly.
18. A method of loading a drum magazine assembly, comprising:
advancing a wheel about a first pivot axis, wherein advancing comprises moving a lever relative to a second pivot axis from a closed position to an open position;
causing the lever to pivot a pawl about the second pivot axis and selectively engage the wheel;
causing the lever to engage an arm to drive the pawl and wheel about the first pivot axis; retracting a follower assembly; and
inserting one or more cartridges of ammunition into the drum magazine assembly.
19. The method of claim 18 , further comprising:
engaging a lever lock to prevent an advancing motion.
20. The method of claim 18 , further comprising:
bracing the drum magazine assembly;
wherein advancing and bracing are performed using a single hand.