G7 BC of 223 55gr Sierra Blitzkings?

dangthathurt · February 1, 2014, 05:57 PM

The title asks it all.

Anyone know the answer or how to get it? I've been googling for quite a while now. This particular bullet is not Brian Litz's book.

Jimro · February 2, 2014, 12:10 PM

Why do you need it? JBM Ballistic will use the provided Sierra G1 numbers when calculating a ballistic table for you, so you don't have to slap together multiple tables calculated from differing starting velocities.

Jimro

splatman · February 2, 2014, 03:16 PM

Call sierra they are real friendly. The G7
BC is more realistic for this bullet,
good luck.

Marco Califo · February 2, 2014, 03:58 PM

1455 .224 dia. 55 gr. BlitzKing .224 55 .157 .271 @ 3100 fps and above
.264 between 3100 and 2550 fps
.250 between 2550 and 2050 fps
.236 between 2050 and 1800 fps
.224 @ 1800 fps and below
http://www.sierrabullets.com/resourc...-coefficients/
http://jbmballistics.com/ballistics/...culators.shtml

Jimro · February 2, 2014, 05:21 PM

Marco,

Those are G1 coefficients. The reason for the different coefficients is that the G1 reference projectile is flat base. The G7 reference projectile has a 7.5 degree boat tail.

Which is why Sierra releases multiple G1 BCs depending on velocity, because the projectile doesn't track well against the G1 reference across the entire ballistic range.

However, if the ballistic software can account for multiple G1 BCs, then it doesn't matter if you use a single G7 or multiple G1 as the output will describe the same ballistic curve.

Jimro

February 1, 2014, 05:57 PM	#1
dangthathurt Member Join Date: February 6, 2012 Posts: 54	G7 BC of 223 55gr Sierra Blitzkings? The title asks it all. Anyone know the answer or how to get it? I've been googling for quite a while now. This particular bullet is not Brian Litz's book.

February 2, 2014, 12:10 PM	#2
Jimro Senior Member Join Date: October 18, 2006 Posts: 7,097	Why do you need it? JBM Ballistic will use the provided Sierra G1 numbers when calculating a ballistic table for you, so you don't have to slap together multiple tables calculated from differing starting velocities. Jimro __________________ Machine guns are awesome until you have to carry one.

February 2, 2014, 03:58 PM	#4
Marco Califo Senior Member Join Date: April 4, 2011 Location: LA (Greater Los Angeles Area) Posts: 2,598	1455 .224 dia. 55 gr. BlitzKing .224 55 .157 .271 @ 3100 fps and above .264 between 3100 and 2550 fps .250 between 2550 and 2050 fps .236 between 2050 and 1800 fps .224 @ 1800 fps and below http://www.sierrabullets.com/resourc...-coefficients/ http://jbmballistics.com/ballistics/...culators.shtml __________________ ............

February 2, 2014, 05:21 PM	#5
Jimro Senior Member Join Date: October 18, 2006 Posts: 7,097	Marco, Those are G1 coefficients. The reason for the different coefficients is that the G1 reference projectile is flat base. The G7 reference projectile has a 7.5 degree boat tail. Which is why Sierra releases multiple G1 BCs depending on velocity, because the projectile doesn't track well against the G1 reference across the entire ballistic range. However, if the ballistic software can account for multiple G1 BCs, then it doesn't matter if you use a single G7 or multiple G1 as the output will describe the same ballistic curve. Jimro __________________ Machine guns are awesome until you have to carry one.

February 2, 2014, 03:16 PM	#3
splatman Member Join Date: April 12, 2012 Posts: 94	Call sierra they are real friendly. The G7 BC is more realistic for this bullet, good luck.