I think I understand BC,: its the measure of the aerodynamics of a bullet and it detimines how a bullet looses velocity with distance. But Barnes is re-evaluting its BC values:

Barnes Bullets is in the process of re-shooting its entire line of bullets to determine new ballistic coefficient (BC) values more useful to today’s shooters. Because accurate BC values are important, particularly for long-range shooting, Barnes fires each bullet under tightly controlled laboratory conditions. The muzzle velocity, time of flight to target and distance to target then goes to a computer programmed to uses this and other variables including temperature, humidity, altitude and barometric pressure to determine the actual BC of the bullet. Some manufacturers only compare their bullets to existing size and shape models to determine a theoretical BC. This theoretical method fails to take into account rifling marks inscribed in the bullet, muzzle yaw, actual bullet velocity and other important variables.

Barnes now measures BC values over 300 yards (they were formerly measured over a distance of 100 yards). Dr. Ken Oehler, of Oehler Research, Inc., suggests that BC values will probably predict trajectories at twice the distance over which the BC value was originally measured. Barnes feels measuring the BC over 300 yards will provide customers with data more useful for long-range shooting out to 600 yards or more.

Over the past five years, Barnes has made slight changes to the geometry of many of its bullets, most notably in the shape of the ogive. Some fairly pronounced secant ogives have been changed to provide more tangent ogives. While slightly reducing BC values, this has significantly improved accuracy. BC values are also affected by multiple rings cut into the shanks of Triple-Shock X-Bullets.

Barnes is currently retesting all TSX bullets, and will post the new values on the company website (www.barnesbullets.com) as they become available. Several new BC values already appear in the latest Barnes catalog. If you have questions about a specific bullet, please feel free to call 1-(800)-574-9200 or email tyh@barnesbullets.com

This implies BC values calcuated for other bullets (ie Nosler) might be inflated?!?! Help me understand this please.

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This implies BC values calcuated for other bullets (ie Nosler) might be inflated?!?!

I think you will find a consensus that Barnes' previous BCs were, ahem, optimistic to put it very mildly. (And were really pretty far-fetched.) Nosler, Sierra, Hornady, and Swift have generally put forth what are usually considered to be pretty accurate numbers.

BCs aren't all that important if you are talking about hunting bullets and normal hunting ranges. Compare the trajectory of a .30-06 220 gr roundnose at 2400 fps and a 180 gr spitzer at 2800 fps. You will find them to be quite a bit closer than most people would think.

To answer the question you really asked, most of your post is just Barnes' prettied up explanation of why their BCs are dropping like the proverbial rock. They finally couldn't put any more lipstick on the pig.

Don't get me wrong, I love their bullets. I had 4 one shot DRT kills this weekend with the 168 TSX out of my .30-06. But the BC numbers just didn't wash anymore. They claimed a BC for their 270 gr .375 X bullet that was 10% higher than the Sierra 300 gr Gameking and 50% higher than the Hornady 270 gr spirepoint.

Like I said, they couldn't put anymore lipstick on the pig and finally had to give it a bath.

LWD

This is a bit confusing.....let me try and help.

Over the last 20 years, at least Sierra, Nosler, and I think Hornady have revised their BC's for their bullets.

The method of measuring can make a huge difference. For example, when shooting a sample of bullets, not all will be perfectly stabilized.....some will have a bit of wobble, and most of those will settle down at longer distances. Since the most stable bullets were the "truest" measure of what the bullet was capable of, that BC was often used. It was also the highest BC--but not necessarily representative of what you could expect as a hunter. This was Nosler's explaination to me of why their BC's changed several years ago.

BC also varies based on conditions, and changes with bullet speed. This is why Sierra publishes different BC's for different bullet velocities. Sierra built a 300 yd indoor range for testing, and corrected a small distance error in the process, which they explained impacted their changes.

Ty at Barnes explained to me that their reshoot was due to the redesign of their bullets. In going to the TSX, they went from a racy secant ogive to a tangent ogive bullet shape, increased the size of the meplat (or hollow nose) and added the grooves. This greatly improved accuracy (since the tangent ogive is more forgiving), improved reliability of opening (with a larger opening), and reduced fouling.

All of those things are improvements in the Barnes bullets, and corrected common complaints from the field--but each hurt the BC.

I am glad that Barnes is admitting that their BC's published in their manuals are not current. Their suggestion to use the published values on their TSX bullets was flat wrong, IMHO. Finding out that the BC of the 270g .375 TSX was really .326 instead of .503.....but it did help expain some things to me.

Let's just say I don't consider Barnes a ballistic leader in the industry any longer.

Hope this helps,

As always, shoot at distance and see how your gun and bullets do....

Dan

Both very informative.

So I gather BC is experimentally determined, not calculated based on the shape of the bullet?

Also, Why do Barnes have such low BC? I thought BTHP was a high BC design. NAB and NBT have much higher BC's than TSX.

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Also, Why do Barnes have such low BC? I thought BTHP was a high BC design. NAB and NBT have much higher BC's than TSX.

Not all the TSXs are boattail designs. Many are flatbase designs. Compare the 225 .338 and the 210 .338. Also, the relief grooves in the shank of the bullet aren't really efficient. It also seems to me that some of them also have secant ogives while others have tangent ogives. Compare the 165 and 168 .30 caliber ones. And the hollow points in some of the larger calibers are rather large resulting in an almost semi-spitzer shape.

The polymer tip and boattail design of the ballistic tips and accubonds contribute to their sleek BC.

LWD

Published ballistic coefficients have been used increasingly as marketing hype. With some manufacturers (Barnes being one of the more notable offenders) the published B.C.'s have gotten so optimistic that they bear diminishing relationships with the actual bullet performance. I think that Barnes has simply decided that the marketing hype is hurting more than helping and has decided to publish B.C.'s more closely related to the real-world experiences of their customers.

Barnes is not the only offender. And the G-1 Ingalls model is imperfect for many bullets. So, always check your actual trajectory under field conditions before relying on published numbers when trying to knock over that quarter-mile shot.