My apologies for the confusion. As some of you guessed, this is my doing.
We are changing the way we establish BC's for our entire line of bullets. We used to use a computer program to predict a BC. The new BC's are the result of test firing the bullets and measuring BC directly. The BC's are an average value from 3000 fps to 1500 fps, which results in a lower number than a BC that's only valid for high speed, however the lower number should result in more accurate long range trajectory prediction because the bullet actually slows down and flies with a lower BC in the end of it's flight.
The .30 cal 210 BC of 0.575 is a mistake. The real value should be
0.616. This was an internal miscommunication, and will be corrected.
As far as I know, the other changes to BC's on box labels have been made accurately. On average, there has been a 4-5% reduction to our advertised BC's in order to bring them into better agreement with test results.
It's important to remember that the bullets themselves have not changed. They are the same design, we're just using a more accurate method to determine the BC's for the same old bullets.
I see that there are some concerns that the BC's were already too low, and this adjustment (reducing BC's) is going the wrong way. These conclusions are based on bullet drop at known distances, which is not a really good way to determine BC since there are so many other variables that come into play, most importantly, the true value of a scope adjustment. For example, if a ballistics program says you need +30 MOA to be zeroed at 1000 yards according to some set of inputs, and you dial +30 MOA and hit high, you may conclude that the BC you're using is too low since the bullet didn't drop as much as predicted. What if your scope actually moved the crosshairs 31 MOA instead of a true 30 MOA? I'm not saying everyone makes this mistake, just one example of a variable that can skew one's perception of BC.
If you have a drop chart that works well using BC that's different than what we advertise, by all means, continue to use what works. Just remember that if you change scopes, you may have to 're-calibrate'.
For those interested in the testing methods used to determine our BC's, you can read a little about it on my website:
Homepage of Bryan Litz - A Bravenet.com Hosted Site
The article on the Berger 155 VLD under 'Palma Bullet Analysis' has the most info on the testing procedure.
There's also an analysis of the 7mm 168 and 180 VLD's specific to LR target shooting, but the ballistics are relevant to hunting as well.
We will always try to improve the accuracy of our information if better means of measuring BC becomes available. The current method is repeatable within +/- 1% most of the time. Also, if it becomes clear that a mistake has been made, we're more interested in understanding how/why and correcting it rather than defending it out of stubbornness.
Those of you who find the BC's to be too low, I suggest measuring your scope adjustments by shooting groups at 100 yards, say 30 MOA apart, and measure to see how far the actual POI moved. This may help to reconcile the new BC's with your actual observed drops. Also remember to make the distinction between MOA and IPHY (Inches Per Hundred Yards).
Thank you all for the feedback, and again, I apologize for the confusion of the new BC's but I believe them to be more accurate (except the mistake on the .30 cal 210 grain VLD).
Take care,
-Bryan
