How dishonest is published data!

[ARlife4me]

I tried to get the best pics I could. The 2nd pic I marked the bullet with a sharpie where it's seated when it's at 2.955". See how little bearing surface is in the neck. The 2nd pic in this post shows the length of what the 7th pic is in post #13.

 

[ARlife4me]

Very true---many people are clueless about this.

And I understand that also. So, why would Nosler change locations for testing as it would be idiotic unless it's to make bc look more appealing on paper. I'm around 2,300' above sea level and haven't tested any bullet on what bc could be. 600 yards is the longest I've shot, but looking forward to reaching out to 1k and beyond which knowing bc is helpful.

 

[Boss Hoss]

And I understand that also. So, why would Nosler change locations for testing as it would be idiotic unless it's to make bc look more appealing on paper. I'm around 2,300' above sea level and haven't tested any bullet on what bc could be. 600 yards is the longest I've shot, but looking forward to reaching out to 1k and beyond which knowing bc is helpful.

I can only refer you to this and there is a plethora of information out there on this subject. In short, there is no single BC. It changes as the range increases because the velocity changes. IMHO you need to read more about this subject because it is not simple but it will become clear. As more accurate measurement methods are discovered the data changes.

https://www.sierrabullets.com/wp-content/uploads/2019/10/BC-chart-rifle.pdf

 

[Calvin45]

When I got into it many moons ago I was told to look at a minimal of 3 different manuals to get an idea of where to start.

Then start low and work up.

I preach the same thing to all newbies.

It's nice now that there's so much published and freely available online.

I consult my hornady book, the hodgdon site, and Noslers data. Sometimes Speer has stuff, Alliant too but navigating their site is a headache.

 

[Calvin45]

It's nice now that there's so much published and freely available online.

I consult my hornady book, the hodgdon site, and Noslers data. Sometimes Speer has stuff, Alliant too but navigating their site is a headache.

Norma is often overlooked but they have some data on their site too and some very useful relative burn rate data to compliment the burn rate charts we already consult. The filled a .308 (I think) with a bunch of different powders, same bullet same charge weight, and got real pressure test numbers and muzzle velocities to compare. I love that kind of real world data.

 

[ARlife4me]

I can only refer you to this and there is a plethora of information out there on this subject. In short, there is no single BC. It changes as the range increases because the velocity changes. IMHO you need to read more about this subject because it is not simple but it will become clear. As more accurate measurement methods are discovered the data changes.

https://www.sierrabullets.com/wp-content/uploads/2019/10/BC-chart-rifle.pdf

Sierra is the only published data that I know of that gives different bc's at various velocities. Again, I know it changes depending on lots of variables. Still the 107mk info along with other published data is way out of whack. When you get to the 130 and up class it's closer to published. Even though this cartridge is built for heavier bullets that are longer and makes it closer to 2.955". Maybe I'll call Sierra and talk about their 6.5prc data. I'll post their reply on Monday if I'm able too talk with them.

 

[Boss Hoss]

Sierra is the only published data that I know of that gives different bc's at various velocities. Again, I know it changes depending on lots of variables. Still the 107mk info along with other published data is way out of whack. When you get to the 130 and up class it's closer to published. Even though this cartridge is built for heavier bullets that are longer and makes it closer to 2.955". Maybe I'll call Sierra and talk about their 6.5prc data. I'll post their reply on Monday if I'm able too talk with them.

They all have different BC's for different velocities. Additionally, there is G1 and G7.

 

[ARlife4me]

Gotta love the free online data FROM bullet manufacturers. No need for shareware! Some Sierra data is free online.

 

[ARlife4me]

They all have different BC's for different velocities. Additionally, there is G1 and G7.

Are you talking in their published data or in general? If, in general I realize it's true among other things associated with bc's.

 

[Boss Hoss]

Are you talking in their published data or in general? If, in general I realize it's true among other things associated with bc's.

Here you go. I have been doing this a long time plus my friend and shooting partner (1k BR) when I was starting out was Rich Maholtz https://bulletin.accurateshooter.com/tag/rich-macholz/

This explains what you are asking. https://bulletin.accurateshooter.co...llistic-coefficients-what-you-need-to-know-2/

 

[doverpack12]

Sierra is the only published data that I know of that gives different bc's at various velocities. Again, I know it changes depending on lots of variables. Still the 107mk info along with other published data is way out of whack. When you get to the 130 and up class it's closer to published. Even though this cartridge is built for heavier bullets that are longer and makes it closer to 2.955". Maybe I'll call Sierra and talk about their 6.5prc data. I'll post their reply on Monday if I'm able too talk with them.

Their data certainly appears to be wrong here

 

[ARlife4me]

I tried to get the best pics I could. The 2nd pic I marked the bullet with a sharpie where it's seated when it's at 2.955". See how little bearing surface is in the neck. The 2nd pic in this post shows the length of what the 7th pic is in post #13.

Here's other pics that didn't get attached for some reason

 

[Calvin45]

An additional word, not to nitpick, but "dishonest" and "incorrect" aren't the same thing at all. I know many people who are earnest and sincere about what they say…and it's demonstrably incorrect. But lying or being dishonest implies willful malicious deception. I very much doubt Sierra is doing that. They just either misprinted something or are totally out to lunch, but not malicious.

I'll give them the benefit of the doubt

 

[ARlife4me]

An additional word, not to nitpick, but "dishonest" and "incorrect" aren't the same thing at all. I know many people who are earnest and sincere about what they say…and it's demonstrably incorrect. But lying or being dishonest implies willful malicious deception. I very much doubt Sierra is doing that. They just either misprinted something or are totally out to lunch, but not malicious.

I'll give them the benefit of the doubt

I state it as pushing by marketing. Many other manufacturers do the same thing unfortunately. I'll admit "dishonest" is an overreach/stretch on my part!