Thursday, July 16, 2009

Maths and Myths

I've taken load data from the Hogdon Reloading Data Center and used it to produce a list of calibers and their estimated muzzle energy in ft/lbs. I used the highest velocity listed for what I consider the most common bullet weight (in grains) for each caliber. The formula for calculating muzzle energy is: (weight x velocity squared)/450450=engergy in ft/lbs [which is a constant for a projectile fired on Earth--not sure where it comes from but that's what it says in my Lee reloading manual.] A note on bullet types: JFP=Jacketed Flat Point; JHP= Jacketed Hollow Point; FMJ= Full Metal Jacket; LSWC= Lead Semi-Wadcutter; JSP= Jacketed Soft Point; LRN= Lead Round Nose.

Now, a word on muzzle energy. Do not choose a caliber solely on muzzle energy. Target penetration, expansion, and (above all) shot placement determine how effective a caliber is for self defense. The FBI determined that a round must penetrate at least 12" in ballistics gel to be able to penetrate deep enough to disturb vital organs. I do not have that data here, but it is available with a little Google-fu. A saying that I find the most helpful when discussing self defense is this "Knockdown power = where you hit and how many times you hit it!". I find the concept of a "one shot stop" to be more than a bit specious.

Here we go:
22LR (from handgun) 40gr LRN @ 1000fps=88ft/lbs

380 ACP 95gr FMJ @ 937fps=185ft/lbs

38 Special 158gr LSWC @ 865fps=262ft/lbs

9x19mm 124gr FMJ @ 1115fps=342ft/lbs

40S&W 180gr JFP@ 1009fps=406ft/lbs

45ACP 230gr FMJ @ 890fps=411ft/lbs

357 Mag 158gr JHP @ 1591fps=887ft/lbs

44 Mag 240gr JHP @ 1522=1234ft/lbs

454 Casull 300gr JHP @ 1716fps=1961ft/lbs

500S&W Magnum 400gr JSP @ 1721fps=2630ft/lbs

So what? Well, I threw in the .22LR as a way of pointing out why I say .380ACP is the BARE MINIMUM I can suggest for concealed carry or self defense. The .22LR has killed people. Probably lots of them. But I still can't suggest it in good conscience. I threw in the .454 Casull and .500 S&W Magnum for the purpose of being absolutely absurd, and to point out a point of diminishing returns. Yes, the .500 and .454 have HUGE amounts of power, but trying to apply that power quickly and efficiently is a task that even master pistoleers find difficult. You are better off sticking between .380ACP and 44 Mag, really most people can stick with the .357, but if you live in a state with bears, your .44 could do double duty as a concealed carry piece and as a trail gun. The .454 and .500 mag are truly shocking in the amount of power you get on tap.

As an aside, I had the chance to fire my hetero-lifepartner's Ruger Alaskan in .454 Casull. I can honestly say it was the only time I've found the amount of recoil from a handgun distracting. I've shot a couple of .44mags, and while they were impressive, the .454 is in a whole different class. I'd advise new shooters to avoid this cartridge as a first or maybe even second handgun. If you don't have at least a decent form, it will make you pay. Don't fear it, but don't take it lightly either.

But back on task, I think we can all see that the eternal debate of "9mm vs. 40S&W vs. 45 ACP" is a fairly worthless argument. The only meaningful difference is the bore diameter. While I am a dyed-in-the-wool 9mm fan, I will readily admit that a larger wound channel is always better than a smaller one. That said, I've seen ballistics gel tests that showed Winchester Ranger hollowpoint ammunition in all three calibers. They all penetrated about 13" and expanded up to the standard "caliber and a half". That means the 9mm ended up at about .53", the .40 at about .60", and the .45 at about .68" respectively. So the argument ends. Buy the one you like the best and shoot the best.

Now for the low end of the power spectrum, the .380 and .38spl. There is a pretty heated debate about shooting full metal jackets vs. hollowpoints in each caliber. The FMJ guys claim that you should rely on shot placement and the superior penetration of the FMJ bullet. The HP guys claim that the larger wound channel of the HP will bring the threat down faster, provided they hit the vitals squarely and have enough energy to penetrate deeply enough. One load for the .38spl that both sides tend to agree on is the "FBI Load" from Federal. The .380ACP has a number of decent JHP loads available, and if your .380 feeds them, I think they're the better way to go. Either way, both of these calibers require a high degree of accuracy to be used in defense. Then again, accuracy is always key, even if you have an Smith & Wesson X Frame chambered in .500 S&W Magnum. Shot placement is king, and penetration is queen.


James said...

Just curious, what's the muzzle energy, bullet weight, and FPS on your 7.62x25 "SMG" rounds?

DC Houghton, esq. said...

I have an 86gr FMJ @ 1400 (estimated, some say 1510)= 374ft/lbs
1510fps would yield 435ft/lbs.

James said...

Oooh one more thing. I took the opportunity to figure out the square area of the holes you could make in a baddie with three guns, an XD-40, my S&W M&P9, and a Brand X mil-spec single-stack 1911. The three guns are going to be pretty close in terms of concealability. I'm comparing the Springfield to the S&W because I think the type of people that would go for a gun in .40 would like the XD (mag pouches with picatinny rails!) and the type of people that would go for a gun in 9mm would go for the S&W (hey, this is really nice!)

Anyway, based on your numbers for expansion:

18 rounds of 9mm: 3.97 sq. in.

13 rounds of .40: 3.68 sq. in.

8 rounds of .45ACP: 2.91 sq. in.

I'm not biased or anything.

I still want a Steyr M10-A1! Oh, guns that don't exist.