Shooting Myths: Knockdown Power
Tom McHale 03.18.14
Knockdown [nok-doun]
adjective
- Capable of knocking something down; overwhelming; irresistible: a knockdown blow.
- Internet lore referring to the ability of large guns like .45s and shotguns to literally knock people off their feet.
Last week, I wrote about Ten Examples of the Internet’s Worst Gun Advice, and that created quite the discussion! A lot of the conversation centered on the issues related to “knockdown power.” Some are still convinced that projectiles from a shotgun shell will knock someone backwards, through a plate glass window, or into the next county. Others got hung up on related issues, like stopping power or lethality.
I decided that this was a great excuse to go to the shooting range and do silly things, so let’s talk about the literal definition of knockdown power. I don’t mean stopping power or lethality or the capability of a cartridge to cause damage. Those things are pretty clear concepts. I mean literal knockdown power. Can a projectile fired from a commonly-available firearm knock someone off their feet? We aimed to find out—and brought a video camera along to document the experiment. There’s a link to the video towards the end of this article.
Since I couldn’t find any volunteers to get “knocked down,” I decided to use a 50-pound bag of sand as a stand-in substitute. Yes, I’m the adventurous sort. I’m stacking the deck in favor of the knockdown power myth. Even though an average Evil Dude is likely to weigh at least three times that, we’re going to see what various projectiles do to an object that weighs just 50 pounds.
One more thing. There was a lot of discussion in the comments last week about kinetic energy, bullets passing through targets, and the concept of energy dumps. So to make sure that our Sandbag Stanley absorbed all the gusto and enthusiasm that each round had to offer, we clothed him in a bulletproof vest. It’s for science, after all.
If this myth carries any weight at all, we’re going to see slight-of-stature 50-pound Sandbag Stanley go flying all over the range when hit, right? We didn’t have a plate glass window to put behind him, so we’re all going to have to imagine that part. Or maybe if OutdoorHub increases its CGI budget, we can add it in during post-production like the Hollywood folks do.
First up on the test was a .45 ACP. We used a full-sized Smith & Wesson E-Series 1911 government model. We didn’t want to risk any velocity loss using a shorter barrel than the original designed by John Moses Browning. We went ahead and skipped the 9x19mm, mainly because so many people are convinced that it couldn’t possibly cause as much destruction as the venerable .45. For ammo we went first-rate: Speer Gold Dot 230-grain hollow points. These leave the barrel at about 890 feet per second. Although the vest would certainly stop a full metal jacket bullet easily, we wanted to get maximum energy dump in the minimum amount of time.
The results? Meh. Even the potent and persuasive .45 ACP failed to budge Sandbag Stanley. Apparently he’s a stubborn sort.
Next up on the list was the AR-15. Some consider it far too powerful to be owned by “civilians.” Others are convinced it lacks effectiveness. We decided not to get caught up in that debate and simply see what Stanley felt about the whole thing. We used standard 55-grain full metal jacket projectiles traveling at 3,000 feet per second.
And? We could barely see anything happen in real time, but we could see the vest twitch when shots impacted during slow-motion replay of the video.
Given Stanley’s resistance to cooperating with the myth, we decided to up the ante and bring in the big guns. Next up was a Mossberg JM Pro 12 gauge. We loaded it with Winchester’s PDX1 Supreme Elite personal defense load. This one carries a double punch, sure to knock Stanley right into the next century. It has a one-ounce slug and three 00 buckshot pellets—all traveling at 1,150 feet per second.
As you’ll see in the video, there was some pretty dramatic energy transfer. The vest stopped the slug and the buckshot pellets, but made about a three-inch deep dent in Stanley. It made for impressive slow-motion video, even if it didn’t come close to knocking Stanley over.
At wit’s end, we decided to donate our shoulders to science and suffer the recoil of 12 gauge one-ounce slugs traveling at a whopping 1,600 feet per second. Our biggest fear, according to internet lore, was that Stanley would simply vaporize and leave a smoking crater in our shooting range. That, and the risk of creating a disturbance in a parallel universe.
Did it work? You’ll have to watch the video to find out.
Just kidding. It did, in fact, knock Stanley over. Barely, and with very little drama. He almost didn’t tip over at all—and he only weighs 50 pounds.
You can see the Adventures of Sandbag Stanley here:
