Ammunition magazine

1. A handgun magazine comprising:

a magazine tube, the magazine tube having a front tube sidewall, a rear tube sidewall, a left tube sidewall, and a right tube sidewall, wherein the magazine tube defines a single-stack portion and a double-stack portion positioned below the single-stack portion;

wherein part of the left tube sidewall and part of the right tube sidewall have a stepped shape between the double-stack portion and an upper tube end, the stepped shape including a first sloped portion adjacent the upper tube end, the first sloped portion extending downward and outward, a substantially vertical section extending down from the first sloped portion, and a second sloped portion extending downward and outward from the vertical section; and

wherein, when the magazine tube is loaded to capacity the magazine retains at least three and no more than four cartridges between a bottom of the stepped shape and the upper tube end.

2. The handgun magazine of claim 1 , wherein a rearward portion of the left tube sidewall and a rearward portion of the right tube sidewall have a linear taper between the double-stack portion and the upper tube end.

3. The handgun magazine of claim 1 , wherein, when the magazine contains three or more cartridges, projectiles of at least three cartridges in the single-stack portion are generally aligned in a single column along the front tube sidewall.

4. The handgun magazine of claim 1 having a capacity of at least 12 rounds of 9 mm ammunition, a tube height of no greater than 90.5 mm, and a tube width of no greater than 20.7 mm.

5. The handgun magazine of claim 1 further comprising:

a baseplate removably attached to a lower end of the hollow magazine tube;

a spring plate;

a magazine spring having a lower spring end connected to the spring plate; and

a follower on an upper end of the magazine spring;

wherein a top surface of the baseplate defines a recess sized and shaped to receive the spring plate therein.

6. The handgun magazine of claim 1 further comprising:

a grip extension on the double-stack portion of the magazine tube adjacent a tube bottom end; and

a floorplate configured to engage the grip extension and the bottom tube end, thereby retaining the grip extension on the magazine tube when the floorplate is installed on the tube bottom end.

7. The handgun magazine of claim 6 , further comprising:

a left bottom lip extending inward from a lower end portion of the left sidewall;

a right bottom lip extending inward from a lower end portion of the right sidewall;

wherein the floorplate defines left and right lateral protrusions constructed to be received between part of the grip extension and the respective left bottom lip or right bottom lip.

8. A handgun magazine comprising:

a magazine tube, the magazine tube having a front sidewall, a rear sidewall, a left sidewall, and a right sidewall, the magazine tube having a single-stack portion and a double-stack portion below the single-stack portion, wherein a forward portion of the left sidewall and a forward portion of the right sidewall each have a stepped shape, the stepped shape including a first sloped portion adjacent the upper tube end, the first sloped portion extending downward and outward, a substantially vertical section extending downward from the first sloped portion, and a second sloped portion extending downward and outward from the vertical section, and wherein a rearward portion of the left tube sidewall and a rearward portion of the right tube sidewall each have a linear taper from the double-stack portion to the upper tube end, wherein when the magazine tube is loaded to capacity the magazine retains at least three and no more than four cartridges between a bottom of the stepped shape and the upper tube end.

9. The handgun magazine of claim 8 , wherein a lower end of the left sidewall has a left bottom lip extending inward from the left sidewall, and a lower end of the right sidewall has a right bottom lip extending inward from the right sidewall.

10. The handgun magazine of claim 8 , wherein, when the magazine contains two or more cartridges, projectiles of at least two cartridges in the single-stack portion are generally aligned in a single column along the front tube sidewall, the single column being the only column of projectiles between the left tube sidewall and the right tube sidewall.

11. The handgun magazine of claim 8 , wherein a width of the magazine tube at the vertical section of the single-stack portion is less than a width of the double-stack portion.

12. A handgun comprising:

a grip portion configured to be grasped by a user and defining a magazine well, the grip portion comprising:

a web region configured to be grasped by a user between a thumb and an index finger, the web region defining a first width; and

a palm region configured to be grasped by a user's palm, the palm region defining a second width greater than the first width; and

a magazine configured to be received into the magazine well, the magazine comprising a magazine tube having a front sidewall, a rear sidewall, a left sidewall, and a right sidewall, the magazine tube having a single-stack portion and a double-stack portion positioned below the single-stack portion, the single-stack portion sized and constructed to retain at least two generally vertically aligned cartridges;

wherein a forward portion of the left sidewall and a forward portion of the right sidewall have a stepped shape between the double-stack portion and an upper end of the magazine tube, the stepped shape including a first sloped portion adjacent the upper tube end, the first sloped portion extending downward and outward, a substantially vertical section extending down from the first sloped portion, and a second sloped portion extending downward and outward from the vertical section, wherein when the magazine tube is loaded to capacity the magazine retains at least three and no more than four cartridge between a bottom of the stepped shape and the upper tube end.

13. The handgun of claim 12 , wherein a rearward portion of the left tube sidewall and a rearward portion of the right tube sidewall each have a linear taper between the double-stack portion and the upper tube end.

14. The handgun of claim 12 , wherein the first width is no more than 25 mm.

15. The handgun of claim 12 , wherein the second width is no more than 27 mm and the first width is no more than 23 mm.

16. The handgun of claim 15 , wherein the magazine tube has a tube width of no greater than 20.7 mm.

17. The handgun of claim 15 , wherein the magazine has a capacity of at least 12 rounds of 9 mm ammunition.

18. The handgun of claim 12 further comprising:

a left bottom lip extending inward from a lower end portion of the left sidewall;

a right bottom lip extending inward from a lower end portion of the right sidewall; and

a floorplate constructed to engage the left bottom lip and right bottom lip when the floorplate is assembled with the magazine tube.

19. The handgun of claim 18 further comprising:

a grip extension on the double-stack portion;

wherein the floor plate engages a front portion and/or a rear portion of the grip extension when the floorplate is assembled with the magazine tube.