New ballistic data at Ballistics By The Inch
One of my favorite websites, Ballistics By The Inch (BBTI), has been updated with more information.
Two more cartridges have been tested: the 9mm Makarov and 9mm Ultra/Police)
They have also tested an additional ten .380 ACP chambered pistols with a variety of ammunition. This has yielded some surprising, at least to me, information. For example, the Bersa Firestorm (3.5" barrel) produces about 10% greater velocity than the Taurus 738 TCP (3.3" barrel) across a variety of different ammunition.
Keep up the good work BBTI!
Hi Charles,
You’re right. There are a considerable number of variables that equations like the Powley & Picatinny equations do not account for. At best, both are pretty good approximations.
For the .308, velocity changes about 150 fps between an 18 inch and 24 inch barrel. You can calculate this using the aforementioned equations but this is also a matter of record as well.
Yeah, ballistics doesn’t typically strike me as an exact science. For example-back when Guns & Ammo was actually a good magazine to read about firearms as opposed to a trade show pamphlet describing how cool things are, one of their writers got fairly into testing out velocity at different barrel lengths with a .308 Remington 700. The really big surprise was when cut all the way down to sixteen inches from 24 or so, it registered a total net difference of something like 50 fps with the considerably more compact barrel.
Barrel diameter & finish have an effect on velocity as does the barrel making process. 9mm barrels are notorious for wild variations. Hammer forged barrels will often shoot faster as the process results in a slightly tapered bore.
Glad to see the data for the Bersa…makes me feel pretty good about my CZ 83 (3.8 inches).
One thing usually not understood is that each firearm is an individual. Some shoot faster, some slower, even if they came off the assembly line. My Bersa may shoot faster or slower than theirs. Worst examples are rifles – chrono’d one 7mm that was a couple of hundred FPS slower than it’s litter mate. Think that one was bored with a tool that was at the end of it’s life span. So, the velocities listed are great for an interesting read, but sort of general guidelines for your specific firearm.
Please note that the left hand column has some interesting examples – the Walther P380 is slower than the PPKs despite having a longer barrel.
Thanks for spreading the word, Steve – always happy to have more people know of the site and our continuing efforts.
More info about the recent tests is on the BBTI blog ( http://ballisticsbytheinch.wordpress.com/ ) as well. We still hope to do our series of ‘cylinder gap’ tests this year, but are waiting for the last of the ammo to become available.
Cheers!
Jim Downey