Rifled barrel

Abstract

A rifled barrel having splines. A projectile has at least one inner fin. A method to spin a projectile to render its shell and its fluid to spin at the approximately the same rate.

I claim: 
     
         1 . A paintball marker including
 a gun stock,   a gun barrel, and   a pneumatic system for propelling a projectile through the gun barrel, the gun barrel having body defining a bore to receive projectiles and a plurality of rotating splines positioned in the bore to rotate projectiles travelling through the bore.   
     
     
         2 . The paintball marker of  claim 1 , wherein the plurality of splines comprises at least two splines. 
     
     
         3 . The paintball marker of  claim 2 , wherein the plurality of splines comprises at least four splines. 
     
     
         4 . The paintball marker of  claim 3 , wherein the plurality of splines comprises at least eight splines. 
     
     
         5 . The paintball marker of  claim 1 , wherein the plurality of splines have tip having a radius of 0.005 inches. 
     
     
         6 . The paintball marker of  claim 1 , wherein the plurality of splines have a height of 0.004 inches. 
     
     
         7 . The paintball marker of  claim 1 , the plurality of splines include a pair of sides that define an angle therebetween of about 90 degrees. 
     
     
         8 . The paintball marker of  claim 1 , wherein the twist rate of the plurality of splines is about one revolution per 18 to 48 inches of a length of travel of the gun barrel. 
     
     
         9 . The rifled bore of  claim 1 , the plurality of splines have about 0.3 to 0.6 twists in the bore. 
     
     
         10 . The paintball marker of  claim 1 , wherein the tips of the splines are convex. 
     
     
         11 . The paintball marker of  claim 10 , wherein the tips of the splines are rounded. 
     
     
         12 . The paintball marker of  claim 1 , wherein the plurality of splines include adjacent splines cooperating to define a gap therebetween, the gap having a gap width, at least one of the adjacent splines having a base with a base width less than the gap width. 
     
     
         13 . A method of firing a projectile having a shell enclosing fluid therein, comprising:
 firing the projectile with a barrel of the paintball marker of  claim 1 ; and   rotating the shell of the projectile and the fluid of the projectile at about the same rate.   
     
     
         14 . The method of  claim 13 , wherein the fluid rotates within about 30% of the rate of rotation of the shell. 
     
     
         15 . The method of  claim 13 , wherein the fluid rotates within about 15% of the rate of rotation of the shell. 
     
     
         16 . The method of  claim 12 , wherein the fluid is a powder. 
     
     
         17 . The method of  claim 12 , wherein the fluid is a liquid. 
     
     
         18 . A projectile including:
 a shell having,
 a front end having a hemispherical surface, 
 a rear end positioned rearward of the front end, the front end having an exterior profile and the rear end having an exterior profile that is substantially different in shape to the front end; and 
 an interior space having a top portion and a bottom portion; 
   a fluid positioned in the interior space of the shell; and   at least one fin extending into the fluid in the bottom portion of the interior space.   
     
     
         19 . The paintball marker projectile of  claim 18 , wherein the fluid is a liquid. 
     
     
         20 . The paintball marker projectile of  claim 18 , wherein the fluid is a powder.