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Two Letters Re: Comparing the Big Three Battle Rifle Chamberings in the United States

Jim:

The recent article [by Kyrottimus] that stated that at 50 yards a typical 45 ACP and 9mm [Parabellum] will have the same energy is wrong.

.45 ACP 230 gr ~390 ft/lbs (528 joules) @ 875 fps (JHP)
9x19mm Luger/Parabellum 115 gr ~385 ft/lbs (521 joules) @ 1,225 fps (JHP)

His additional assumption, that bullets will slow equally in an air mass, is also wrong.

I noticed that he listed the fps for a 9mm cartridge at 1,225 fps. This is the energy for a 9mm +p+ range cartridge, while comparing it to the 45 ACP ball cartridge, not a +p rated bullet. How convenient for the crowd that believes 9mm and 45 to be "equivalent". The Winchester Ranger +p 230 gr ball is rated at 985 fps out of my barrel and it's ballistic coefficient makes it retain more energy at 50 yards than the lightweight 9mm 115 gr cartridge. So while not trying to get into the age-old 9mm versus 45 ACP fight, he's perhaps unintentionally dishonest in his comparison. I would hazard a guess that the data itself was simple cut and pasted, and the writer is unused to vetting his writing.

I also found a big error, where the writer says: "Note that grains in bullet mass differ from from the "grains" of smokeless powder (nitro-cellulose) propellant, which is not used in this article." He couldn't be more wrong. I thought there was something up when he equated grain weight to carats and then to grams - I don't think this is a reloader or someone more conversant with ammunition - no reloader I know could ever make this mistake. [JWR Adds: I think that what he meant write was that a physical grain of powder does not necessarily weigh one grain. But you are correct that powder is weighed in the same "grains" scale as bullets.]

When he talks of the destabilization of a typical rifle round, he also describes what actually happens erroneously, when referring to the centrifugal force of the cartridge "failing", and "the laws of inertia, resistance, velocity and mass" being the deciding factors after the "spin fails". He uses big words, but I'm positive he doesn't know what the interactions of those forces are. Using words like 'critically destabilizes' sounds like he was quoting something again, and not instructing the reader. You know, as do I, that [Col. Martin] Fackler [the lead author of the NATO Emergency War Surgery manual and numerous ballistics studies] explained all of this stuff very simply and very succinctly - and rotational forces are a primary reason for jacket and bullet fragmentation, they do not "usually fail" as he writes. - Jim H. in Colorado

Jim:
"Point blank" is not just vaguely "... a few yards from the muzzle" as Kyrottimus stated.

Here is the official definition:
In external ballistics, point-blank range is the distance between a firearm and a target of a given size such that the bullet in flight is expected to strike the target without adjusting the elevation of the firearm (see also gun). The point-blank range will vary with the firearm and its particular ballistic characteristics, as well as the target chosen. A firearm with a flatter trajectory will permit a nearer minimum and further maximum point blank range for a given target size, while a larger target will allow for a longer point blank range for a given firearm.

We need to teach the correct usage of terms, not colloquialisms. - Beach

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