Ballistics by the Inch?

[rolyat63]

Ballistics by the inch

This is an interesting site I stumbled across. These fellas dropped some coin and some time to develop a decent amount of data with respect to the most popular SD rounds. I've seen some here discussing the impact of the longer barrels of a carbine and the shorter barrels of a snubbie.

From their website:

Why "ballistics by the inch"? Well, just about forever people have wondered what kind of trade-off one made in choosing a gun with a short barrel - how much power were you giving up for convenience/concealability? There has been a lot of anecdotal information available - comparing this 2" .38 to that 6" .38, or a longslide .45 to an officer’s pistol with a shorter barrel - but there hasn’t been much in the way of consistent research made available to the average gun owner. In the 1980s American Rifleman did some tests using a .44 mag revolver, cutting the barrel down from 18" to 1", and back in the 1930s someone did something similar with a 30-30. But just try and find that data quickly. And further, how does that data compare to your 9mm or .32? Do they all lose power at the same rate? Are some ammos better for your purpose than others?

We were curious just exactly what the drop-off in velocity was for a given caliber over a range of barrel lengths, and using a variety of available ammunition. So, we decided to do some actual testing. And, we wanted to make this information freely available as a service to gun owners everywhere. This website is the result.

The site has full documentation of the project (over 6,000 rounds fired), easy to see summation tables for the results, clickable graphs showing the curve of each ammo over the 18" - 2" barrel lengths, an associated blog, and a lot more. You can download the entire database for your own use as well. Stop by, check it out, spread the word to others who may be interested.

[DefensiveCarry.com]

[farronwolf]

Pretty good info.

I need to apply for the job the next time this gets done. As long as it is on someone else's dime.

[Ram Rod]

Wow! That's all I've got to say is--WOW!

[Al Lipscomb]

Interesting data. You can sometimes find the specs for a bullet that will tell you what velocity range it was designed for. Combine that with these charts and you have some useful data.

[rolyat63]

How energy is being delivered at these lengths and velocities? I'm sure several here already know this formula but I'm gonna share for those who don't.

Weight x Velocity x Velocity / 450400 = Energy

Take for instance a .357 Sig 125 grain Corbon from a 16" barrel results in approximately 823.9 ft pounds.

.357 Sig 125 Grain Corbon
125 x 1723 x 1723 / 450400 = 823.9 ft pounds

[tns0038]

Very interesting... Thanks

[Jim Downey]

Hey everyone!

One of the good things about launching the Ballistics by the inch site has been finding some other great gun forums that have linked to us. Now I'll never get anything else done . . .

Thanks for the good comments about the site - sorry, we won't be hiring anyone for the next round of testing this spring (when we'll be testing these calibers: .327 Federal Magnum, .41 Magnum, 10 mm). But you're always welcome to stop by the blog and chat or tell us what to do next.

Cheers!

Jim D.

[Rusty Bouquett]

I must say, this information was a bit eye opening, to say they least. From my evaluation of it I'll not be looking for any "one shot stops" from my handguns.

[Jim Downey]

Well, yes, Rusty - they *are* just handguns, after all. That said, nothing has changed in terms of what we knew about handgun effectiveness just because we now have the velocity data. The conclusion I drew from the tests was what I've pretty much always known: the shorter the barrel, the more you're going to lose in terms of raw power, relative to the power you would otherwise gain in that caliber from a longer barrel.

But I'd still rather have a 4" .357 (SIG or Magnum) than an 8" .25.

Jim D.

[QKShooter]

Hey Jim D. ~~~~~>
Really highly worthwhile and interesting.
Your time & effort much appreciated.

[Jim Downey]

Thanks, QK. It was a fun project, for all the work involved.

I like the site here - may not participate a whole lot, as I tend to lurk and learn from others on gun boards. But I will be around and add my $0.02 when appropriate.

Jim D.

[Bob O]

Great site!

Thanks for all the work that went into it!

Bobo

[retsupt99]

Unique site...lots of info...well organized.

[quantum36]

Fantastic work!


I typed in the results of one of the .357 mag data sets
and plotted it .

Looks like the data can be fitted with a logarithm function, with possible parameters being a multiplicative constant and the base of the logarithm.

[rolyat63]

Fantastic work!


I typed in the results of one of the .357 mag data sets
and plotted it .

Looks like the data can be fitted with a logarithm function, with possible parameters being a multiplicative constant and the base of the logarithm.

Did you see the raw data in excel? http://www.ballisticsbytheinch.com/data.xls