## Ballistic Coefficient

01:08:03 | Chapter 2 from Applied Ballistics for Long Range Shooting: Ballistic Coefficient. Bryan and Mitch cover the history and current use of Ballistic Coefficients in long-range shooting. There’s a little math, but mostly the concepts and ideas are discussed. After listening to this, you should have a decent grasp of what BC is, how to use it, and what its limitations are.

*Listen to an excerpt:*

Great episode! With all of the data you have compiled with CDMs- would you be able to publish the average BC variation for bullets? Because BC variation is not published by most manufacturers-empirical data would be extremely useful. Specifically, what are you seeing for BC variation of Berger 245 grain 30 cal EOL?

Thats a great question Scott, we have published some of this data in the past after PDM events. The problem is that there are a number of factors that play into what your BC variation will be including round count, how you clean your barrel, launch dynamic, bullet design, manufacturing quality, etc. Because of all of this, it is very difficult to say the BC variation of this bullet is X as a definitive statement. So, before we publish that kind of data, we will need to figure out the best way to baseline it across the board. All of that said, it is something we are looking into.

Now, specifically on the 245gr 30cal EOL, I would expect those to be in the 0.8 to 1.0 % BC SD variation range straight out of the box in a barrel that is in good condition, if you OAL sort them into 0.005″ groups and point them with a Whidden pointing die, we regularly have them test in the 0.3% variation range.

First of all, thank you for sharing valuable information with us. I have a question. If we don’t know the ballistic coefficient of an ammunition, how do you calculate the friction coefficient manually?

Hello Murat, I am not sure what you mean by friction coefficient? If you are referring to the form factor, there is no simple way to calculate it and the only real way to arrive at that value is to measure the drag of the bullet. That being said, by looking at a number of bullet designs and their respective form factors, you can train your eye to estimate the form factor to with in a few percent. Especially if you look at bullets of similar weight and caliber.

İf we don’t know the B.C. of an ammunition how do you calculate the drag coefficient manually ? Thanks Do you know any Cd calculate formula