Home Forums Hunting & Shooting Ask The Gunwriters NOVEMBER - Ask John Barsness Questions About "THE REALITIES OF BALLISTIC COEFFICIENT"

Hi Guys:

I want to thank John Barsness (Mule Deer) for his latest exclusive Campfire article.

Please use this space to ask John questions about THE REALITIES OF BALLISTIC COEFFICIENT

Enjoy, folks!

John, did I miss something? What wind velocity were you assuming?

Great write up.

10 mph full value.

Shooting 243 and with all the BC that the 105g Amax brings, with a launch speed around 3000fps, I've often wondered if one wasn't better shooting a good plastic tipped boat tail bullet like the 87g Vmax at 3250fps for foxes, dogs, goats and similar.

Running the numbers and making some realistic decisions about how far away you can actually hit something the size of a fox, it's certainly possible to make a case for the lighter, faster projectile.

We're sure spoiled for choice these days, which is good news for retailers I suppose!

Thanks for illuminating the path, John! I was looking for reasonably priced 168 gr FMJ's for my AR-10 when I found obscenely priced 150's at evergladesammo.com (now even cheaper at $199/1000 with free shipping!). I've believed all of the hype of bc for quite some time, but I ran the numbers in a ballistics software program and the difference was nil except for about 100 ft/lbs of energy out to 800 yards; and up to that point, the 150's actually perform better in many aspects. Your article confirmed my hypothesis! Thanks again.

Cool! Glad you liked it. Great deal on the bullets.... :-)

I messed with some numbers awhile back and it seems to me that the "gains" (essentially meaning lest drift) of increased BC tend to level off.

Not sure if my method was scientific or even appropriate for the idea, but I used a 150gr bullet at 3,000 FPS and ran drift at 1000 yards.

.1=542"
.2=264"
.3=168"
.4=144"
.5=83"
.6=64"
.7=53"
.8=45"
.9=39"
1.0=34"


Anyway, I'm no Brian Litz....but I stayed in a Holiday Inn Express once.

Good article!

My favorite high BC 7mm bullet is the 162 Amax. At 3200 fps the trajectory matches the dots in a 6x36 LR about exactly at 400, 500, and 600 yards.

John, thanks for the great article on BC. I use that as a bullet selection factor in long range shooting. However, BC relies on the accuracy of the information put out by the bullet manufacturers. I ran across a study published in 2012 by four cadets at the US Air Force Academy. That study concluded that most bullet manufactures do not accurately set out the ballistic coefficients of their bullets. I read the article with interest. My conclusion is that it is not an accident, believing that if it were accidental, the results would be scattershot around true bc.
My reading the article, including an analysis of standard deviations, in an attempt to measure intentional missreporting vs measurement error, it appears that at least one manufacturer was significantly overstating BC intentionally.
My conclusion is that BC may be a starting point, but beware of manufacturers claims of BC. The proof is tight consistent groups rather than BC Claims.
The article is available at: http://www.dtic.mil/dtic/tr/fulltext/u2/a554683.pdf

rblum100,

Yeah, I've seen that report, which is why I advise buying Bryan Litz's book BALLISTIC PERFORMANCE OF RIFLE BULLETS, based on his range-testing and calculations. Have used Bryan's results a lot, which has saved me lots of ammo!

Sometimes manufacturers make the mistake of testing bullets only at 100 yards for BC, which naturally results in higher BC's than over longer distances. But I have definitely seen some "competition" in listed BC's over the decades. It reminds me of what an outfitter buddy once noted about getting a booth at a sports show, in the middle of a bunch of other elk outfitters. Somebody will ask one outfitter what his "success rate" is, and if the answer is 60%, the outfitter next to him will claim 65%!

Thanks for another interesting article John. One caution in doing such experiments in software is that the flight characteristics of a given style of bullet can change as weight changes. Here's a link to a YouTube video that analyzes the Laupa 7mm 180 and 150 grain Scenar-L bullets using Laupa's custom drag functions. The 180 grain matches up well with G7 while the 150 grain matches up better with G1. Not something I expected and without knowing that a comparison using either G7 or G1 for both bullets may not be accurate.

I see Hornady is using Doppler radar to produce custom drag functions for their 4DOF calculator, but I didn't see anything for the .204 Ruger at this point, so it would be hard to say if the 45 and .223 75 grain V-Max bullets both match up well with either G7 or G1.

Very interesting!

The interest in longer-range shooting has sure spurred some innovation in calculating/measuring BC's.

My Remington 280 in 139GRN on a T/C ProHunter platform and a 100yrd zero with a BDC Reticle at 3 power 1st hash mark is 404yrds second 654yrds third 849yrds and thats with accutually a 7mm Bullet

I dunno what your point is, but turning the magnification of any second-focal plane variable down increases the distance between the hashmarks. It has nothing to do with ballistic coefficient.

Extremes in spread and sd of long range loads, 800+ yds are more trouble some than worries about BC

Great article MD. Just read so late to party. Would like your thoughts on following. If shooting 6.5CM w/142ABLR at 2700 using a ballistic program do I really want to plug-in the Nosler published BC of .719 or some lesser value (down to the G1 of .320) and then start shooting to verify? Thoughts/suggestions? If it helps, 4-16 Viper HS-T w/VMR-1 using Strelok+ program. Mike, NRA life member.

John, here`s my question: I asked a simple question on a post,got some real negative replies.here is the question that`s in the lever-big bore and you may have read it too ? >> do you consider the 300 win. mag big bore? my thought since its a lever ,has much more power,accuracy and ability to shoot at much longer ranges ,plus this type lever rifle handles newer higher pressure cartridges.

Pete,

No, I don't consider the .300 Winchester magnum big bore, but such opinions are always subjective. Some older African hunters considered the .450/.400 Nitro-Express and .416 Rigby "medium bores."

John, thanks for quick answer, here`s two more Questions : why doesn`t campfire have 2 different site post? one for the better quality single shot rifles ? the other is lever rifles like the BRL Brownings that handle the newer higher pressure cartridges ?