Ballistics by the inch

Join the party.

All along, we’ve said that if someone wanted to take the time, trouble, and expense to do some additional research along the lines of our protocols, that we’d be happy to include their data on our site. This is particularly true if it helped expand the selection of “real world guns” associated with the data for a given caliber/cartridge. Well, for the first time someone has expressed an interest in doing just that, prompting us to come up with an outline of what standards we feel are required for making sure it relates to our previous tests.

The biggest problem is that ammo manufacturers may, and do, change the performance of their products from time to time. This is why we have on occasion revisited certain cartridges, doing full formal chop tests in order to check how specific lines of ammo have changed. That gives us a benchmark to compare other ammo after a period of several years have passed, and shows how new tests relate to the old data.

But without going to such an extent, how can we be reasonably sure that new data collected by others using their own firearms is useful in comparison to our published data?

After some discussion, we feel that so long as any new testing includes three or more of the specific types of ammo (same manufacturer, same bullet weight & design) we had tested previously, then that will give enough of a benchmark for fair comparison. (Obviously, in instances where we didn’t test that many different types of ammo in a given cartridge, adjustments would need to be made). With that in mind, here are the protocols we would require in order to include new data on our site (with full credit to the persons conducting the tests, of course):

  1. Full description and images of the test platform (firearm) used in the tests. This must specify the make, model number, barrel length, and condition of the firearm. Ideally, it will also include the age of the firearm.
  2. That a good commercial chronograph be used. Brand isn’t critical — there seems to be sufficient consistency between different models that this isn’t a concern. However, the brand and model should be noted.
  3. Chronographs must be positioned approximately 15 feet in front of the muzzle of the firearm used to test the ammo. This is what we started with in our tests, and have maintained as our standard through all the tests.
  4. That five or six data points be collected for each type of ammo tested. This can be done the way we did it, shooting three shots through two different chronographs, or by shooting six shots through one chronograph.
  5. All data must be documented with images of the raw data sheets. Feel free to use the same template we used in our tests, or come up with your own.
  6. Images of each actual box of ammo used in the test must be provided, which show the brand, caliber/cartridge, and bullet weight. Also including manufacturer’s lot number would be preferred, but isn’t always possible.
  7. A note about weather conditions at the time of the test and approximate elevation of the test site above sea level should be included.

We hope that this will allow others to help contribute to our published data, while still maintaining confidence in the *value* of that data. Please, if you are interested in conducting your own tests, contact us in advance just so we can go over any questions.

 

Jim Downey

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September 9, 2016 Posted by | .22, .223, .22WMR, .25 ACP, .30 carbine, .32 ACP, .32 H&R, .327 Federal Magnum, .357 Magnum, .357 SIG, .38 Special, .380 ACP, .40 S&W, .41 Magnum, .44 Magnum, .44 Special, .45 ACP, .45 Colt, .45 Super, .450 SMC, .460 Rowland, 10mm, 9mm Luger (9x19), 9mm Mak, 9mm Ultra, Anecdotes, Data, Discussion., General Procedures | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , | Leave a comment

‘Rifleshooter’ does .223/5.56 chop tests down to 6″

A very nice companion to our .223 chop tests:

223 Remington/5.56mm NATO Barrel length versus Velocity- Short Barrels- 6 to 14 inches

In 223 Remington/5.56 NATO, velocity versus barrel length: A man, his chop box and his friend’s rifle, we cut the barrel of a factory Remington 700 chambered in 223 Remington back one inch at a time and recorded the average velocity for four different 223 Remington and 5.56mm NATO cartridges.  The data set generated from that post provided imperial values for muzzle velocities from 26″ to 16.5″.  A few readers suggested mounting the barrel in a pistol and continuing the test for shorter barrels- we liked the idea.  In this experiment, we gathered data using the same barrel from the first 223 Remington/5.56mm NATO experiment (on a pistol action), with the same four kinds of ammunition from 14″ to 6″.

 

Good protocols, good documentation, good data. And between his different tests, he covers a wider range of barrel lengths than we did, and has some different loadings — so what’s not to like? Go check it out, and bookmark it to share with others!

 

Jim Downey

November 29, 2015 Posted by | .223, Data | , , , , , , , , , , | 1 Comment

That’s … unexpected.

Checking this morning’s stats (which I do pretty much every morning, over my first cup of coffee, just out of idle curiosity), I saw that there was an incoming link … from the Washington Post.

???

So I followed the link back, read the article, and didn’t see anything in it about BBTI. However, given the topic of the article (actually, it’s an editorial), I figured that I’d find the incoming link in the comments. And here it is:

enzo11

3/13/2015 3:58 PM CST [Edited]

There are actually many very short barreled pistols ( 7 inch, on down to Derringer-sized under-3 inch) available chambered for the .223 round.

But what this idiot of an author forgets is basic physics : the shorter the barrel, the lower the muzzle velocity. The lower the muzzle velocity, the less penetrating power the bullet has – by a large factor ( the energy is partially determined by the square of the velocity).

For a chart on muzzle velocity for different barrel lengths:

http://www.ballisticsbytheinch.com/223rifle.html

For what that does to the available energy:

http://www.ballisticsbytheinch.com/2011graphs+/223…

 

OK, BBTI wasn’t actually cited by the Washington Post. But it’s still amusing.

 

Jim Downey

March 15, 2015 Posted by | .223, Data, Discussion., Links | , , , , , , , , , | 1 Comment