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

It looks like I kicked a hornet’s nest a little with my article, so here is a little clarification on my part.

To reply to Jim H. In Colorado:
“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)”

“Wrong” is a harsh term for so many variable loads for any type of ammo. I basically used the NATO loading data for the 9x19mm in a 5″ barrel pistol in a U.S. Military M9.

Muzzle Velocity 375 meters per second (1,230.3 feet per second)
Muzzle Energy 569.5 Newton meters (430 foot pounds)
See: www.Gun-Shots.net: “9mm bullet weights typically vary between 95 and 147 grains. These bullets leave the average pistol barrel from 930 up to 1,450fps.”

And from another source:
Ball 115 gr (7.45 g) 1,125 ± 90 fps (343 ± 27 mps)
(If using this, +or- 90 could mean 1,035 fps min or 1215 fps max)
M882 Ball 112 gr (7.26 g) 1,263 ± 5 fps (385 ± 1.5 mps)
(If used, drop ~35fps off for a hand-loaded typical 115gr projectile to get ~1,225fps)

Sources included above; you’ll also find references to U.S. military .45ACP loadings as well.
I “dumbed” my stats in the article down to accommodate for ~4.5″ pistols or some commercial defense loads. Please revise any old reloading manuals to which you may be still referring.
“His additional assumption, that bullets will slow equally in an air mass, is also wrong.”
I didn’t claim anywhere that bullets slow equally to each other, but what I did say was a SINGLE bullet will decelerate at a constant rate assuming the atmosphere is at a constant pressure. Allow me to quote myself:
“…so long as the air resistance remains constant, so too will the rate of deceleration of the projectile.” (not “projectiles”)
The statement is of a singular bullet, not comparing one to another.
” 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…”
See above reference to NATO 9x19mm cartridge loads.
…while comparing it to the 45 ACP ball cartridge, not a +p rated bullet.”

I was merely comparing NATO spec to NATO spec (apples to apples, so to speak), maybe I should have listed that from the get-go. NATO ammo in 9×19 may be applied to handloaders using like weighted projectiles with similar sectional density/ballistic coefficient to allow for better “energy dump.”
“How convenient for the crowd that believes 9mm and 45 to be “equivalent”.”

They aren’t. I never said they were. I’ll pick .45ACP nine times out of ten because beyond 50 yards it retains more of its power, further. It also doesn’t over-penetrate as much at closer range so it’s usually more efficient at energy deposition than the 9x19mm at both closer and longer ranges (in my opinion). Please don’t jump to conclusions, I said they were “equal in net force to 50 yards”, not in their energy deposition properties.

” 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.”

That is a completely true statement, but it’s not pertinent to the point I was trying to make in my article.

” 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.”

If I was somehow inaccurate or dishonest in my assessment of handgun data (used mostly to compare to rifles, not so much to each other), I apologize. It was not my intent.

I used many other sources but most of those were mostly to reassure my own assessments and did not feel pertinent to list every one (those included above with the NATO 9×19 data in the M9 as well as .45 ACP are just a few).

It was not “cut and pasted” and my vetting as a writer is irrelevant. I admit, I over-generalized in my article for the sake of length. Perhaps I should have began with preamble stating so to avoid further reactions. If someone feels the need to add, amend or correct my article, please do so. I don’t know everything about firearms, ballistics or physics. But let’s be honest, anyone can pit two different calibers and different types of loads and get plenty of different results. I am trying to compare “like loads” as close as possible (barrel length, ammunition purpose, cartridge source, etc.).

Again, my intent was not to imply that one may be better than the other, or to start contentious arguments. I was simply trying to, in generalized manner, display physical properties of energy in moving projectiles.

” 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.]

JWR is correct. It is my fault, however, for not better wording the statement. It should have read something like this:
“A grain is a unit of lead mass measurement. Note that a “grain” of measurement is originally based upon lead weight and is in no “weigh” equal (pun intended) to a single grain of powder (as powder comes in either extruded/stick or ball/sphere). It is a unit of measuring mass, not individual powder grains. The unit if measurement “grain” is the same no matter what you are weighing; bullets, powder or the amount of pepper in your pepper shaker”

” 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”.”

I thought I was using basic words. “Spin Failing” is not a technical term; not by a long shot (no pun intended). Critical destabilization is often thrown around as a buzzword. When a bullet hits something harder than air, it’s going to slow down. Longitudinal friction (the direction of the bullet’s travel) is not the only friction a bullet encounters when slowing down. Roll/Spin Friction (via the bullet’s spin) also occurs. If that friction is enough to slow its spin down beyond the point of stabilization, it will usually begin to tumble (if it is back-heavy). Otherwise it can do a myriad of other unpredictable things.

I am positive I’m close enough to be more right than wrong in my basic sentiments.

“Using words like ‘critically destabilizes’ sounds like he was quoting something again….”

Maybe I should have used words like “Break apart” or “loses stabilization” or “slows down very fast” to appease those who may find my motives or style of writing questionable. I am sorry if I am not 100% to-the-point in detail and that I have often over-generalized to truncate an already lengthy article. I stand by the basic concept of energy dynamics in firearms ballistics, though.

And in response to the comments by Beach:
“Point blank” is not just vaguely “… a few yards from the muzzle” as Kyrottimus stated.”
Correct. Again, my mistake of over-generalization. When dealing with new readers, I should have made a terse, but appropriate differentiation between “point-blank” and the usual closest correct distance to set up a chronograph (which yields “muzzle” data). Beach closed with is:”We need to teach the correct usage of terms, not colloquialisms.” I agree completely, and concede this point to you good sir. – Kyrottimus