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Berger Smoke and Mirrors?

FearNoWind

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Joined
Jul 10, 2012
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North Central Valley California
All of the data I've collected on the 7mm Berger 180gr Hybrid VLD Target includs a BC of .659. When I fire up the Berger Ballistics Calculator at Ballistics | Berger BulletsBerger Bullets use the feature " Select a bullet from the list or enter in the properties below" the calculator automatically enters a BC of .349. Anybody got any idea what's going on there? Maybe I'm off base - it happens. :D
 
Because the G7 is a better model for modern, long for caliber bullet designs. I certainly don't think it is "Smoke and Mirrors".
 
For reasons only the tech wizards can explain (I sure can't articulate it well enough) the G7 profile matches the VLD bullet shape's actual performance more closely than the older G1 profile. When you do trajectory validation using multiple distances, you usually find less "disagreement" between the various drops. Not to say you can't validate a load very well with G1, just that G7 is better for VLD shapes. If Phil from Berger catches this I am sure he'll give a good explanation.
 
The program is trying to keep you from doing something wrong, select a G1 profile bullet and it will load a G1, you've selected a G7 profile bullet.
 
OK, guys, let's start over. lightbulb
If you order a box of Berger Hybrid Target Match 7mm 180 gr bullets today the box label will read G7 BC = .345; G1 BC = .674.
Use the Berger Ballistics Calculator I made reference to on page 1 of this thread and select the same bullet - you can't even get a G1 BC factor and the G7 information (.349) doesn't agree with what's on the boxed bullets. It's a minor detail but I tend to like everything squared up in little boxes.
Don't get your diapers in a knot. It's a pretty straight forward question (OK - I admit I could have worded it more clearly :rolleyes:)
I wonder if some of you guys read the labels on the stuff you reload or just wing it. I just want to be certain that I'm not missing something in the reading interpretation.
 
Bullet manufacturers have been using bc as a selling tool. G1 bc looks much better as it is a bigger number. Then if a company inflates 10% on the G1 it looks even better. Most purchasers of bullets have no idea what to do with a bc, so it makes no difference to them, but they bought the product. Very few shooters will ever shoot past 300y let alone 500y. They can't tell the diff in the bc. Hats off to Berger for getting it as accurate as possible.

From my point of view, bc is a varying value determined by the combination of rifle and bullet. The bc value will be affected in different ways by different rifles. If a shooter is really ringing out his equipment he may have to make an adjustment to the given bc value in order to get things to line up. I look at bc as a fluid number that I use with all the data collected from shooting at multiple yardages, and then use to get my drops to work out.

The G7 value works out better than the G1 value, and once the G7 value is accurate for the given equipment set up, it will line up much farther out with less tweaking to the data.

We decided that we would market our bullets with G7 values for the same reason that Berger is using it. It's better. Most modern bullets are better served with the G7 rather than the G1. The only good reason to use the G1, as a manufacturer, is to try and falsely look better than you are in order to boost sales.

No smoke and mirrors here. Berger is trying to help you shoot better.

Steve
 
As Rocky said, G1 will always be a higher number than G7. Berger was the first to start using G7. You really don't want to use the G1 in your ballistics calculator when you have a G7 profile as the output data will be wrong. Just to see the difference, go to JBM Ballistics and run that bullet first with G1 then with G7. Pay particular attention to when the bullet is expected to become trans-sonic.

Also, as was stated earlier Berger continues to research their products so the BC value was recently updated for some bullets.

The G1 profile is a tangent ogive with a flat base. This produces a much shorter bullet in a particular weight than the G7 profile which has a secant ogive with a boat tail base. Just as with boats, the longer, sleeker profile produces less drag due to the different bow (nose) and stern (tail) wakes. A bullet passing through air produces much the same wake as a boat going through water. Incidentally, the longer a boat is the faster it will go with the same propulsion.
 
No "Smoke and Mirrors" at all. You just need to understand G1 and G7 BC's. It has been explained very well in this thread. As for the minute changes in BC's from box to current website data, That's just Berger doing what they promised us a few years ago. To do the best job to represent their bullets with accurate BC data. As further testing and technology reveals new or updated data, they update to give us the very best in accurate data. I have been shooting and hunting with Bergers for 10 years now. Truck loads of game taken and target hits in excess of 3000 yards. You can trust what they offer for BC's. My deadliest rifle is at 34 and zero for one shot kills, from 200 yards to 1300. This rifle uses the G7 BC right off the Berger box and always has. That is not only a representation of accurate drops, but also accurate wind drift data. It takes accurate BC's to accomplish this.

Jeff
 
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