who do you believe the real ballistic coefficient?

[nitis]

On another forum talking about all the different 257 bullets and someone chimed in with the interbond having a better bc than the AccuBond.

Well nosler says 418 and hornady say .375 for theirs im not stupid the higher number is better

But this person said that Bryan Litz claims the BC of the 115 gr bt is only .399 so the 110 AB must be less

Anyone know any inside to what this is all about?

 

[Desert Fox]

Believe yours!

B.C is not written in stone. It can change from rifle to rifle, from condition to condition, velocity change from supersonic to transonic etc. etc. Use the one published by the bullet manufacturer, verify it in the field and adjust accordingly.

 

[corbin9191]

Not to hog your post, but how do you find the B.C. of your bullets out of your rifle? Is there a formula?

 

[rick smith]

Does it even matter to most hunters? It is said that most deer are killed at 100yds or less. How many 300+ yds shots do you take at deer or other game? The boattail doesn't make that much difference until you get to 300yds. Pick the bullet that shoots best in your rifle at the distances you really hunt and then practice at those distances. I think most loaders get wrapped up in the wrong numbers and want the very highest velocity and BC yet at 300yds their groups and shooting ability can't make use of any actually advantage.Rick.

 

[3006savage]

The BC coefficients listed by manufactures vary dramatically based on the velocity they are travelling at . Most manufactures of course list velocities that show the highest BC for marketing purposes.

There is a G7 BC model that minimizes this variance but few manufacturers list a G7 BC for their bullets. Hopefully they will in the future.

One thing I have noticed is that the Hornady BC claims have proven very accurate when tested by actual measured results.

Brian Litz has tested several of the "too good to be true bullets" out there and they in fact did not come close to the claimed BC. Surprise Surprise.

 

[JD338]

BC values are subject to several variables such as velocity, altitude, temperature, humidity, etc. Sierra list BC at various velocities where as Nosler uses an average. Needless to say, "actual" BC will vary for all of us.
Berger is the only one using the G7 Drag model as far as I know.

JD338

 

[FOTIS]

Not to hog your post, but how do you find the B.C. of your bullets out of your rifle? Is there a formula?

Chrony that load and shoot it from 100 to 600 yards and average the bc

 

[nitis]

I understand that everything changes and has an effect. but as teh bullet sits still on my bench what is it they all start with something right?

I mainly want to know for when I turn in my load data to leupold for a custom turret

 

[GB300wm]

I always shoot in my dope. A computer program is never 100%, but the bc that the manufacturer gives you is always a great starting point. I've never been that far off to 600 yards. Maybe a click or two, but not off the target. Start at 200 yards and move out 100 yards at a time to whatever distance you can go.:grin: :grin:

 

[Desert Fox]

Not to hog your post, but how do you find the B.C. of your bullets out of your rifle? Is there a formula?

You do need a program. I have an old one that I downloaded way back. Believe it or not, it's in DOS. You need two chronograph though. One at 12 feet in front of you and the other downrange at 100 yards. You then input the velocity at 12 ft. and the velocity at 100 yards. The program will tell you your actual B.C.

Another way of doing it is to shoot your rifle using the factory listed B.C for the particular bullet that you're going to use. Set your target at least at 500 yards or better yet at 600. Dial your elevation according to your ballistic chart and measure the actual bullet drop relative to your chart. Make sure to take note of the atmospheric condition during the shoot. Fire at least 10 rounds and then average it. Chances are, your chart and your actual result may differ. Tweak the B.C until your field result and your chart matched accordingly. It's much easier if you have ballistic program like Exbal or Horus to take to the field. I say it's a good investment.

Just to give you an example. During the sighting in session in my match two Sundays ago, I was shooting low at 1000 yards. I used the listed factory B.C of the 300 grain SMK, which is .768 in my calculation. Now I know, I'll be a bit off on the B.C since I had trimmed the meplat of the SMK to make them all uniform. How low? According to Sinclair as much as 8%. I tried 6% which dropped my B.C to around .725.

I feed the new B.C on my Exbal and my elevation went from 21.5 MOA to 22.5 MOA. I was spot on after that. Now my elevation was correct but the wind was another matter.

 

[Ridge_Runner]

here is what I do

sight in at 300 yards, use a large target and shoot at 400,500,and 600 yards measure your actual drops.now open up your ballistic program, tweak the BC until your actual drops match the chart in the program.

You need the actual MV, and the lower the ES the closer your data will be, my actual BC for a nosler 160 AccuBond (published at .531) is .62, using this number in my exbal program I've taken deer out to 1350 yards.

I've tested hornadys, lapua's, nosler's, and bergers for actual BC, only one has matched the makers published #.
RR

 

[corbin9191]

Not to hog your post, but how do you find the B.C. of your bullets out of your rifle? Is there a formula?

You do need a program. I have an old one that I downloaded way back. Believe it or not, it's in DOS. You need two chronograph though. One at 12 feet in front of you and the other downrange at 100 yards. You then input the velocity at 12 ft. and the velocity at 100 yards. The program will tell you your actual B.C.

Another way of doing it is to shoot your rifle using the factory listed B.C for the particular bullet that you're going to use. Set your target at least at 500 yards or better yet at 600. Dial your elevation according to your ballistic chart and measure the actual bullet drop relative to your chart. Make sure to take note of the atmospheric condition during the shoot. Fire at least 10 rounds and then average it. Chances are, your chart and your actual result may differ. Tweak the B.C until your field result and your chart matched accordingly. It's much easier if you have ballistic program like Exbal or Horus to take to the field. I say it's a good investment.

Just to give you an example. During the sighting in session in my match two Sundays ago, I was shooting low at 1000 yards. I used the listed factory B.C of the 300 grain SMK, which is .768 in my calculation. Now I know, I'll be a bit off on the B.C since I had trimmed the meplat of the SMK to make them all uniform. How low? According to Sinclair as much as 8%. I tried 6% which dropped my B.C to around .725.

I feed the new B.C on my Exbal and my elevation went from 21.5 MOA to 22.5 MOA. I was spot on after that. Now my elevation was correct but the wind was another matter.

That's exactly what I needed to know. I have the crony and the exbal already, so now all I need to do is go shooting! Thank you!