Ballistic Coefficient or (B.C. for those who hate math)
Years ago, starting down the precision rifle path my craving for “data” and “numbers’ was strong. Part was my need as a trainer and SWAT team leader, but like most new to the craft it was fun and interesting. Most of my focus was on terminal ballistics, but I dived deep into everything police sniper or precision rifle related. Books, facts, figures, data and more data. Like most zealots while I thought I was interesting to all, most could not care less and thought I was nuts. Finally, I was offered a reality check by my lead sniper. Diving deep at a simple question he rolled his eyes and put up his hand and said, “Dave, that’s great, but all I care is it goes off, goes where I aim it and does what it’s supposed to when it gets there, the rest is just plain boring.” Point taken, it was just not required to do his job and of zero interest to most. Later on, roles were reversed when it came to Ballistic Coefficient (BC). With books, seminars, and programs Einstein would wonder about all I wanted to know is what it meant for me. After decades of shooting precision rifles, carbines, and most anything with a trigger out to a mile here is my simple minds take on BC.
BC, what is It?
Ballistic Coefficient in simple terms is a measurement of how efficiently a bullet travels through the air on its way to a threat or target. The higher the number the less they may drop over distance and the less they are affected by the wind given a certain velocity. The numbers you see are based on two models, G1 for old, flat based or blunt bullets, G7 for modern boat tail or sharp pointed bullets designed for longer range. It is a means of comparison so make sure you are comparing against the same model. Numbers using G7 will be lower compared to G1 to a point, it’s a different base model, just be certain you are comparing G1 to G1 and G7 to G7 and you are good.
It is one factor amongst many used in ballistics programs to determine a bullet path (trajectory) given its velocity from your rifle and the atmospheric conditions. It also is a means to sell bullets. Like much of the industry it has become as much sales gimmick as measure of value. The numbers are often inflated or measured under different conditions to publish the highest numbers. Still, it can be valuable to many it’s just important to determine if you are part of that group.
So what is “Long Range”?
What is considered “long range” has changed over the years. Starting as a police sniper the number was 300 yards, in some cases it was 600 yards. I remember “experts” stating that a .223 could not get hits beyond 300 yards, if so, they were not lethal. Shooting a 308 at 600 yards was “pure luck” and 1000 yards was just “dropping stuff” on them. Today we know that was complete nonsense and was more about the nut behind the rifle than the bullet in the chamber. With the increased interest in long-range shooting those numbers have changed significantly with shooters getting hits with .223 at 800 yards easily. Leaps in technology, training, and manufacturing have helped for sure, but increased interest has also improved the trigger puller moving that out a bit. In my experience long range starts at 600 yards with 1000 to 1200 yards logistically being the limit for most shooters. Beyond that it becomes a whole other endeavor and BC is critically important.
At what point should I care?
The point at which BC is important depends on what you are doing. As a police sniper with a typical deployment across the street it meant nothing. No realistic engagement within civilian law enforcement is long enough for BC to matter, training or competition maybe, but not deployment. If you are trying to put ten rounds in the same hole at 600 yards it may be critical, more for consistency and repeatability, but important. Those who are in need of lead on a silhouette (steel or threat) it is less important. If your longest distance is 600 yards it means little for the average shooter. For most who cannot access a range longer than 300 yards it is pretty meaningless. In my experience at or beyond 600 yards you start to see a difference in bullet drop and wind deflection in head-to-head comparisons so for me that’s where it starts. Anything beyond that and it becomes increasingly valuable.
With access to steel to a mile I have tested dozens of bullets in numerous calibers head-to-head. Shooting a 12” round steel at 600 yards is where things seem to change. For instance, shooting Black Hills Ammunition 69 grain and 77 grain TMK head-to-head out of a Zevtech AR with a 16” barrel there is little difference to 500 yards, some at 600 yards. Where you really start to see the 77 TMK take is at 800 and 1000 yards. The 77 TMK has a higher BC not only due to weight, but it’s shape. Same thing from 6.8 SPC, 6.5 CM, 308 and at least a dozen other calibers including 300 Norma and 300 PRC out to a mile. If shooting beyond 600 yards looking for hits on smaller targets, especially in the wind the higher BC can be helpful, increasingly so the farther you go out.
Velocity is important, not only in how the BC was measured, but in application. My best example is using Hornady’s 95 grain VMAX and 140 grain ELDM from my 18.5” barrel in the Desert Tech SRS A1. Muzzle velocity on the 95 grain is 3140 FPS, the 140 grain only 2540fps. At 600 yards the 95 grain holds its own, even in the wind, at 1000 yards 140 grain takes over and at 1200 yards there is no comparison. Since nothing will present itself to me past 600 yards with that rifle the 95 grain is my preferred round. For comps, or just shooting longer ranges it is the 140 grain or similar. Same is true for our Hornady 53 grain VMAX hand load in .223. With a muzzle velocity of 3400 fps it is a hard hitting laser out to 300 yards with less recoil, the higher BC of the larger bullets provide no real value at all. It’s why Velocity matters, and it’s critical when comparing BC’s to take into account what you are doing, rifle you are doing it with and how far it will need to go.
Ballistic Coefficient and its value in long range shooting can be incredibly detailed, there are weeklong classes taught by expert ballisticians and mathematicians on it. The internet is a treasure trove of “experts” that talk about it in nauseating detail, most having never actually used a rifle. It has spawned an entire genre of shooters that don’t actually shoot long range, they just work out what it “should” do on a computer and post it on Internet sites, blogs, and social media. Nothing wrong with that, for now at least America remains a free country, study until your brain hurts. But, for most of us it is nothing more than a simple means of comparison that only matters if we are shooting at long range, and although old fashioned, the best comparison remains lead on steel, and that is a ton more fun and far more valuable.