One more question (this time on BC's)
03-01-2012, 07:59 PM
#1
Nontypical Buck
Thread Starter
Join Date: Nov 2005
Location: Illinois
Posts: 1,482
One more question (this time on BC's)
One more question, does anyone know the real world BC for the .40 cal 185 Lehigh? I am getting ready to do some long range shooting next month and I want to do my homework first. I have 100 of the 185 Lehighs and about 120 of the 200 grain SST's to shoot up (although there's no way I'm shooting all of them in 2 days).
Hornady lists the 200 SST as having a BC of .235 if I recall, although several people have posted here that the real-world BC is more like .215.
I would imagine the 185 Lehigh would have a lower BC than the SST, but I do not have any idea of how much lower. Ideas anyone? Figure the muzzle velocity to be about 2,000 fps....
Hornady lists the 200 SST as having a BC of .235 if I recall, although several people have posted here that the real-world BC is more like .215.
I would imagine the 185 Lehigh would have a lower BC than the SST, but I do not have any idea of how much lower. Ideas anyone? Figure the muzzle velocity to be about 2,000 fps....
03-02-2012, 04:55 AM
#4
Nontypical Buck
Join Date: Aug 2008
Location: Rapid City, South Dakota
Posts: 3,732
Based on my experience shooting the 200g SST, it seems the published BC of 0.265 is relatively close.
An example of how this BC is kinda verified is the 450 yard jug thread.
Using the BC of 0.265 the ballistic program calculated a zero at 450 yard would require the 200g SST to be 19.79" high at 100 yard. The elevation dial on the scope was turned to 19.75 moa, and the shot taken. Had the BC of 0.265 not been somewhat close to accurate, the hit never could have been made.
An example of how this BC is kinda verified is the 450 yard jug thread.
Using the BC of 0.265 the ballistic program calculated a zero at 450 yard would require the 200g SST to be 19.79" high at 100 yard. The elevation dial on the scope was turned to 19.75 moa, and the shot taken. Had the BC of 0.265 not been somewhat close to accurate, the hit never could have been made.
03-02-2012, 05:42 AM
#5
Boone & Crockett
Join Date: Aug 2004
Location: Idaho
Posts: 11,703
oldsmellhound
BC of a bullet is based on the velocity that you might be shooting it at. If you were to shoot it a high velocity the BC number may be higher than if you were shooting it at a lower velocity. Companies always publish the better velocity.
To find the real worl velocity, often people will shoot a bullet through two chronographs, one at the muzzle and one at 100 yards, then do the math to compute the real BC.
The numbers that Lee provided are probably established in that manner. From that you would need to know the load he chose to shoot it with.
Sierra bullets is the only company that I know of that provides BC's by the a spread of velocities the bullet may be shot at.
If you go here. Choose one of their bullets they will provide you a range of ballastics over the flight of the bullet.
http://www.sierrabullets.com/index.c...e=handgun&BC=1
This would be an example of a 40mm - 180 grain bullet.
Bullet NameDiameter inchesWeight grainsSectional DensityBallistic Coefficients.400 dia. (10mm) 180 gr. JHP
.400 180 .161 .140 @ 1150 fps and above
.160 between 1150 and 1000 fps
.170 between 1000 and 850 fps
.120 @ 850 fps and below
If you look on the actual Sierra site the information shown above will make more sense.
BC of a bullet is based on the velocity that you might be shooting it at. If you were to shoot it a high velocity the BC number may be higher than if you were shooting it at a lower velocity. Companies always publish the better velocity.
To find the real worl velocity, often people will shoot a bullet through two chronographs, one at the muzzle and one at 100 yards, then do the math to compute the real BC.
The numbers that Lee provided are probably established in that manner. From that you would need to know the load he chose to shoot it with.
Sierra bullets is the only company that I know of that provides BC's by the a spread of velocities the bullet may be shot at.
If you go here. Choose one of their bullets they will provide you a range of ballastics over the flight of the bullet.
http://www.sierrabullets.com/index.c...e=handgun&BC=1
This would be an example of a 40mm - 180 grain bullet.
Bullet NameDiameter inchesWeight grainsSectional DensityBallistic Coefficients.400 dia. (10mm) 180 gr. JHP
.400 180 .161 .140 @ 1150 fps and above
.160 between 1150 and 1000 fps
.170 between 1000 and 850 fps
.120 @ 850 fps and below
If you look on the actual Sierra site the information shown above will make more sense.
Last edited by sabotloader; 03-02-2012 at 05:44 AM.
03-02-2012, 06:33 AM
#6
Nontypical Buck
Thread Starter
Join Date: Nov 2005
Location: Illinois
Posts: 1,482
Thanks everyone! Those numbers will at least get me in the ballpark for when I go shooting next month. I'm planning on setting up some 200 yard and 250 yard targets and shooting with the 200 SST and 185 Lehigh and doing some comparisons....
