Lyman 48th edition Handbook Question.

William_IV · August 29, 2005, 12:48 AM

In every load recipe in the top right hand corner there is 2 numbers I couldn't find out from the book what these numbers referred to.

Example on page 356 upper right corner says BC: .139
and right below it says................................SD: .130

Yeah i'm new to this...! I think SD= Sectional Density but i'm not sure.
BC=??? I have not..A.. clue... Does anyone want to enlighten me?

BigSlick · August 29, 2005, 01:53 AM

BC=Ballistic Coefficient

DAVID NANCARROW · August 29, 2005, 01:53 AM

BC=balllistic coefficient of friction. i.e., how well the bullet flies through the air.

Smokey Joe · August 31, 2005, 12:27 AM

S. D. of a bullet is its weight in pounds divided by the square of its diameter in inches. Well, so what??

This is what: "The higher the S. D. of a bullet in a given diameter, the heavier and longer that bullet will be. This is important to several factors, including the B. C. of the bullet. However, from a big game hunter's standpoint the most relevant measure of S. D. is that with all else being equal, the higher the S. D. of a bullet, the better its ability to penetrate."
Lyman's 48th edition Reloading Manual, pg. 105

Same source: "The ability of a bullet to retain its velocity is expressed as the ballistic coefficient. This is a measure of how aerodynamic a bullet is and how well it cuts through the air." The higher the number, the better the bullet slips through the air, and the less velocity it loses over a given distance.

Bottom line: All else being equal, longer, heavier, pointier-nosed bullets go through both air and targets better than shorter, fatter, rounder-nosed bullets. Simple, no?

August 29, 2005, 12:48 AM	#1
William_IV Member Join Date: March 4, 2005 Location: Phoenix AZ Posts: 76	Lyman 48th edition Handbook Question. In every load recipe in the top right hand corner there is 2 numbers I couldn't find out from the book what these numbers referred to. Example on page 356 upper right corner says BC: .139 and right below it says................................SD: .130 Yeah i'm new to this...! I think SD= Sectional Density but i'm not sure. BC=??? I have not..A.. clue... Does anyone want to enlighten me?

August 29, 2005, 01:53 AM	#2
BigSlick Senior Member Join Date: January 25, 2005 Location: Texas of course Posts: 277	BC=Ballistic Coefficient __________________ Nobody likes war, but if you find yourself in one - fight for those you serve with and to make the trip home. Show mercy to those that deserve it and a relentless, ruthless, cunning evil to those who don't.

August 31, 2005, 12:27 AM	#4
Smokey Joe Senior Member Join Date: July 14, 2001 Location: State of Confusion Posts: 2,106	Sectional density S. D. of a bullet is its weight in pounds divided by the square of its diameter in inches. Well, so what?? This is what: "The higher the S. D. of a bullet in a given diameter, the heavier and longer that bullet will be. This is important to several factors, including the B. C. of the bullet. However, from a big game hunter's standpoint the most relevant measure of S. D. is that with all else being equal, the higher the S. D. of a bullet, the better its ability to penetrate." Lyman's 48th edition Reloading Manual, pg. 105 Same source: "The ability of a bullet to retain its velocity is expressed as the ballistic coefficient. This is a measure of how aerodynamic a bullet is and how well it cuts through the air." The higher the number, the better the bullet slips through the air, and the less velocity it loses over a given distance. Bottom line: All else being equal, longer, heavier, pointier-nosed bullets go through both air and targets better than shorter, fatter, rounder-nosed bullets. Simple, no? __________________ God Bless America --Smokey Joe

August 29, 2005, 01:53 AM	#3
DAVID NANCARROW Senior Member Join Date: November 5, 2000 Location: Wyoming Posts: 1,761	BC=balllistic coefficient of friction. i.e., how well the bullet flies through the air.