Sunday, March 02, 2014

Thousandths, Grains, Foot-Pounds . . . Oh, My!

by Cori Tyler

Which round is the best overall for defense?  It’s one of those ageless debates.  I’ve already written a little about this, but it bears a little more coverage.  This discussion has brought forth some great one liners:

Q:  Why do you carry a .45?
A:  Because they don’t make a .46!

10mm, because let’s face it, if you don’t carry it, it’s because it hurts your girly wrists.

.40, like 9mm, only for men.

9mm, because anything that needs shooting needs shooting 15 times.

You get the idea.  What is the real difference between all of these?

Let’s look at the numbers.  Bullet diameters are .45 = .452, 10mm = .40, 9mm and .380 = .355, .38 and .357 = .358.  Let’s think about that for a minute.  The smallest common diameter bullets differ from the largest common diameter by .097 inches.  97/1000 of an inch.  Not a lot of difference.  Especially in proportion to the surface area of a person’s body – the target.

Bullet weights for common calibers range from around 115 grains to 230 grains.  Now, a grain is equal in weight to about 1/7000 of a pound.  So, we’re talking about a range between 2/125 and 4/125 of a pound.  Compared to the relative size of a 200 pound target, there still isn’t a lot of difference.

Is velocity the major difference?  Most loads in the range we’re discussing here fall between 850 and 1500 feet per second (fps).  That’s a lot of range.  This might be the difference, right?

So, how about the oomph we’re hitting a target with, muzzle energy?  Let’s look at some of the usual muzzle energy figures for common rounds:

.45 ACP                                 230gr Gold Dot                                 404 ft-lb
10mm Auto                            155gr Tac-XP                                    774 ft-lb
.40 S&W                                180gr Golden Sabre                        412 ft-lb
9mm Parabellum                  124gr +P Gold Dot                           410 ft-lb
.357 Magnum                       125gr HP XTP                                  624 ft-lb
.38 Special                            110gr +P JHP                                   269 ft-lb

As a frame of reference, most automobile manufacturers recommend tightening lug nuts on the wheels to 80 ft-lb.  So, the .38 Special hits with roughly 3 ¼ the force we tighten our wheels to.  Next, the 9mm, .40, and .45 are at just over five times that force.  .357 comes in just under eight times as much and 10mm at just under 10 times.  We’re talking a spread of 505 ft-lb.

Contrary to Hollywood portrayals, people shot with handguns aren’t picked up and thrown across the room.  Officers have taken .357s in the vest and continued standing and fighting.  So, how much better or worse are the other rounds above going to fare?

Here’s the point I’m working toward:  caliber selection, or even ammunition selection, may not be the most important factor for us to consider deciding on our defensive tools.  It’s really a pretty small difference in all measurable areas.  Let’s face the fact many people more knowledgeable than me have pointed out.  Handguns are under-powered.  You’re better armed with a rifle or shotgun.  Those don’t tuck inside the waistband so well, though.

So, we’re not going to stun them with power anyway (says the guy who loves his 10mm).  We’d damn well better pick a handgun and ammo combination that A)  we can afford, 2)  are comfortable for us to carry and shoot, and III)  shoot well.  A friend of mine used to say he’d rather be missed by a .44 than hit by a .22.  That illustrates it pretty well.  None of those numbers above mean a single thing if they’re misses while defending yourself.

So, along with the three factors in the last paragraph, possibly the most important thing to consider is . . .

. . . wait for it . . .

. . . shot placement!

How you train, practice, and perform might just be the most important factors in surviving a defensive shooting situation.  If you can put your rounds on target, reliably, in the necessary amount of time, you’ll have a good chance of survival.


So, find the handgun you like, the ammo you like, and train as much and as constructively as you can.  If you can get outside training from quality instructors, seize that opportunity.  If you can’t, take exercises you’ve learned in the past and repeat them.  Start slow.  Safety first.  You’ll be amazed how fast you’ll see an improvement.

No comments:

Post a Comment