Projectile and firearm system

1. A cartridge for a firearm, the cartridge comprising:

(a) a projectile having (i) a body portion extending along a longitudinal axis, the elongate body portion having a transverse dimension configured to engage the bore;

(ii) a tail portion defining a rear end of the projectile and including a plurality of radially extending tail fins, the radially extending tail fins having a leading edge longitudinally intermediate the elongate body portion and the rear end of the projectile; and

(iii) a stem connecting the elongate body portion and the tail portion, wherein the stem has a stem diameter less than the transverse dimension;

wherein the body portion, the tail portion, and the stem are colinearly disposed along a longitudinal axis and define a fixed integral assembly with a projectile center of pressure and a projectile center of mass, the projectile center of pressure being longitudinally intermediate the rear end of the projectile and the projectile center of mass; and

(b) a casing coupled to the projectile, wherein at least a portion of the tail fins are disposed within the casing.

2. The cartridge of claim 1 , wherein the elongate body portion includes a nose section including an increasing taper along the longitudinal axis and a trailing section having a decreasing taper along the longitudinal axis.

3. The cartridge of claim 1 , wherein the elongate body portion includes plurality of radially extending body portion fins.

4. The cartridge of claim 1 , wherein the elongate body portion has a first density and the tail portion has second density, the second density being lower than first density.

5. The cartridge of claim 1 , wherein a length of the elongate body portion is greater than a combined length of the stem and the tail portion.

6. The cartridge of claim 1 , wherein tail fins have a diameter less than the bore caliber.

7. The cartridge of claim 1 , wherein the leading edge of the tail fins defines an increasing radial dimension toward the rear end along the longitudinal axis.

8. The cartridge of claim 1 , wherein the elongate body portion has a homogenous density.

9. The cartridge of claim 4 , wherein the elongate body portion includes a first component having a third density and a second component having a fourth density, each of the third density and the fourth density being different from the first density.

10. The cartridge of claim 1 , wherein the casing and the projectile define a charge volume within the casing.

11. The cartridge of claim 1 , wherein the casing and the projectile define a charge volume within the casing and further comprising a solid propellant retained within the charge volume.

12. The cartridge of claim 1 , wherein the transverse dimension is a diameter of the body portion.

13. The cartridge of claim 1 , wherein at least a length of the tail portion includes a cavity extending along the longitudinal axis, and wherein the cavity includes at least a closed end.

14. A projectile for passing through a bore of a barrel of a firearm, the bore having a bore caliber, the projectile comprising:

(a) an elongate body portion having a body diameter and a first density, wherein the body diameter is a caliber diameter;

(b) a tail portion defining a rear end of the projectile and including a plurality of radially extending tail fins, the radially extending tail fins having a leading edge longitudinally intermediate the body portion and the rear end of the projectile; and

(c) a stem connecting the body portion and the tail portion, wherein the stem has a stem diameter less than the body diameter;

wherein the body portion, the tail portion, and the stem are colinearly disposed along a longitudinal axis and define an integral one piece assembly with a projectile center of pressure and a projectile center of mass, the projectile center of pressure being longitudinally intermediate the rear end of the projectile and the projectile center of mass;

and wherein each tail fin includes at least two of a radial taper, a longitudinal taper, and a bottom surface.

15. The projectile of claim 14 , wherein for each tail fin the leading edge of the tail fin has a smaller cross-sectional area than a trailing edge of the tail fin.

16. The projectile of claim 14 , wherein the bottom surface connects two adjacent tail fins.

17. A projectile for passing through a bore of a barrel, the bore having a bore caliber, the projectile comprising:

(a) an elongate body portion extending along a longitudinal axis to define an elongate body portion length, the elongate body portion having a plurality of radially projecting body portion fins extending along the longitudinal axis, the body portion having a transverse dimension, wherein the transverse dimension is a bore caliber;

(b) a tail portion defining a rear end of the projectile and including a plurality of radially extending tail fins, the radially extending tail fins having a leading edge longitudinally intermediate the body portion and the rear end of the projectile; and

(c) a stem connecting the body portion and the tail portion, wherein the stem has a stem diameter less than the body diameter; and

wherein the body portion, the tail portion, and the stem are colinearly disposed along a longitudinal axis and define an integral one piece assembly with a projectile center of pressure and a projectile center of mass, the projectile center of pressure being longitudinally intermediate the rear end of the projectile and the projectile center of mass.

18. The projectile of claim 17 , wherein the body portion fins terminate within the elongate body portion.

19. The projectile of claim 17 , further comprising a barrel having a bore, wherein the bore has a cross section configured to slideably receive the projectile.

20. The projectile of claim 17 , wherein the body portion fins extend along at least 25% of the elongate body portion length.