tommygirlMT
11-23-2009, 11:03 PM
Okay, so I'm currently involved in a debate over on another forum regarding penetration effectiveness of various types of shotgun slugs. A self proclaimed expert who has never fired a full bore (0.73-ish) diameter round ball slug out of a 12ga. gun is claiming that there is no way it could have a penetration advantage over a standard 12ga. 1oz foster slug because it has both a lower sectional density and a lower BC and therefore is an inferior projectile if penetration is desired.
Considering that a 0.730" RB of pure lead weighs in at 580+ grains and 1-oz is equal to 437.5 grains and both are of the same diameter some simple math to calculate sectional density it shouldn't be hard to conclusively and mathematically prove that a full bore round ball does indeed have a greater sectional density then a 1-oz 12ga. slug which is nothing more then a flimsy thin sheet of lead folded over on itself in a thimble shape.
However, the BC component of the argument I'm having a little more difficult of a time with. I have found printed/published documentation that a 12ga. 1-oz foster slug has a BC of about 0.07 but I have been unable to obtain any documented information regarding the BC of a round ball that I have direct access too. I did find this though:
Ballistic Coefficient In order to calculate the trajectory of a bullet in flight, its ability to push aside the air and retain energy must be known. This property is known as the bullet's Ballistic Coefficient (BC). To calculate an accurate BC for any given bullet requires actually shooting it many times at various velocities, and measuring it's change in velocity over range. There is a simple way to approximate the BC for a round ball, though, so we can play around with theoretical trajectories.
For a round ball traveling more than 1300 fps:
B.C. = Ball Wt. in grains divided by (10640 x ball dia. x ball dia.)
Example: For a .535 ball weighing 230 grains, 230 divided by (10640 x .535 x .535) = a BC of .0755. Lyman's Black Powder Handbook gives a BC of .075 for a .535 in. ball, so the agreement is good. This formula courtesy of "Lee in Denver"
That's almost all the way down on the bottom of this page here:
http://members.aye.net/~bspen/math.html
Which if I use that formula, a round ball of 0.730" diameter has a BC of about 0.10 which is a higher BC then a foster slugs 0.07 thus meaning I can show that both statements this guy made are BS and then I can do some structural engineering analogies to show how a round solid sphere is one of the strongest 3-dimensional shapes possible and will be deformed the least on impact. I also have some pictures of actual penetration tests with both foster slugs and round balls to finish nailing this down.
There is one hole in my response so far though. All I have is that formula from so no-body for determining the RB's BC. Supposedly there is a chart showing the BC for various size RBs in Lyman's Black Powder Handbook. I do not own that publication and have been unable to locate this information in published form else-where. Would someone who has that book please look this up for me and post that chart for me. Page number reference would be appreciated as well.
Considering that a 0.730" RB of pure lead weighs in at 580+ grains and 1-oz is equal to 437.5 grains and both are of the same diameter some simple math to calculate sectional density it shouldn't be hard to conclusively and mathematically prove that a full bore round ball does indeed have a greater sectional density then a 1-oz 12ga. slug which is nothing more then a flimsy thin sheet of lead folded over on itself in a thimble shape.
However, the BC component of the argument I'm having a little more difficult of a time with. I have found printed/published documentation that a 12ga. 1-oz foster slug has a BC of about 0.07 but I have been unable to obtain any documented information regarding the BC of a round ball that I have direct access too. I did find this though:
Ballistic Coefficient In order to calculate the trajectory of a bullet in flight, its ability to push aside the air and retain energy must be known. This property is known as the bullet's Ballistic Coefficient (BC). To calculate an accurate BC for any given bullet requires actually shooting it many times at various velocities, and measuring it's change in velocity over range. There is a simple way to approximate the BC for a round ball, though, so we can play around with theoretical trajectories.
For a round ball traveling more than 1300 fps:
B.C. = Ball Wt. in grains divided by (10640 x ball dia. x ball dia.)
Example: For a .535 ball weighing 230 grains, 230 divided by (10640 x .535 x .535) = a BC of .0755. Lyman's Black Powder Handbook gives a BC of .075 for a .535 in. ball, so the agreement is good. This formula courtesy of "Lee in Denver"
That's almost all the way down on the bottom of this page here:
http://members.aye.net/~bspen/math.html
Which if I use that formula, a round ball of 0.730" diameter has a BC of about 0.10 which is a higher BC then a foster slugs 0.07 thus meaning I can show that both statements this guy made are BS and then I can do some structural engineering analogies to show how a round solid sphere is one of the strongest 3-dimensional shapes possible and will be deformed the least on impact. I also have some pictures of actual penetration tests with both foster slugs and round balls to finish nailing this down.
There is one hole in my response so far though. All I have is that formula from so no-body for determining the RB's BC. Supposedly there is a chart showing the BC for various size RBs in Lyman's Black Powder Handbook. I do not own that publication and have been unable to locate this information in published form else-where. Would someone who has that book please look this up for me and post that chart for me. Page number reference would be appreciated as well.