Knockdown Power (related to shot placement thread)

[Spinner]

In the "shot placement on deer thread" there was considerable talk about knockdown power from large, heavy bullets.

There's a book called "The Sharpshooter" written by a Kiwi guy and his son (Bruce and Matt Grant). It is out of print now, which is a shame because its excellent. This guy took a scientific approach to all sorts of subjects and gives practical information about rifle shooting and the reasons behind it all. One of the things the Grants do is de-bunk the "knockdown" myth.

They made an artificial deer from a couple of wooden nail boxes filled with sand on wooden legs. The "deer" was about the weight and height of a small deer. They shot the artificial deer with a .303 from 50 yards and recorded the deflection effect caused by the bullet. They then hit the artificial deer with a cricket ball (throwing it by hand) from around 10 yards IIRC and recorded the deflection. Surprisingly enough the deflection of the artificial deer, i.e. the knockdown effect, was about the same. The experiment was replicated .... I'm sure my brief description doesn't do it justice.

The conclusion being that being shot with a .303 from 50 yards was the same sort of impact as being hit with a hand thrown cricket ball from about 10 yards ..... and neither was likely to knock a deer off its feet through mechanical action alone.

From my knowledge of biomechanics I'd suggest that the "knockdown" that hunters observe in the field is probably the result of the interruption of nerve pathways and muscular control and co-ordination caused by the bullet's impact and wound path rather than physically knocking an animal off its feet.

Spinner

 

[lycanthrope]

A bowling ball doesn't have to move fast at all to make major power factor. I'll take that over a bullet any day!

Tissue disruption in a vital area is all that matters. Large amounts of tissue disruption can make up for a poor shot to some degree as it amounts to more leeway, but more meat damage if you hunt.

 

[HankB]

There's no such thing as "knockdown power" if you're talking about hunting big game with common cartridges. It's a basic conservation of momentum issue - if the recoil of the gun doesn't knock YOU down, the impact of the bullet will not knock down a large animal. If the critter drops right there, it's due to the nervous system's reaction to the shock and trauma of the bullet impact.

If you use a 12 gauge slug on a chipmunk, that's a different story.

 

[DigMe]

Yeah, I think this is more common knowledge among people on these boards because for the most part I think we tend to do more research into all aspects of shooting. Also, these kinds of things tend to get hashed out and debunked here on a regular basis. I think the knockdown power myth is more common among the general public and the casual shooter/hunter. This month's edition of Field and Stream debunks the myth as well. That's good because there are probably a lot more people who believe that myth that are readers of F&S than there are here at this website.

brad cook

 

[H&Hhunter]

To me "knockdown" is the ability of the round you 're using to break major bone. There are actually two ways to create "knockdown" or the preception thereoff.

As mentioned previously a CNS disconect and the other is a major bone structure break down such as a double shoulder breakage or a busted pelvis.


Often times a shoulder shot that "ices' a critter on the spot has gotten into the spine as well. the spine sits much lower than most people think on most quadrapedic mamals.

I whole heartdly agree that there is no such thing as knockdown as far as the rifles ability to bowl big game over from the power of the round alone with out some biomechanical or electrical interferance..

 

[twoblink]

My buddies in TX call it "shoulder bustin'" .. For hogs. They just need the round to be able to break both shoulders.. 2 bad shoulders = a hog that ain't gettin' away..

But I can't stand it when Hollyweird shows a guy FLYING backwards from a 9mm round..

 

[444]

" If the critter drops right there, it's due to the nervous system's reaction to the shock and trauma of the bullet impact."

Whatever. To me, this is knockdown power.
I think this is one of those areas where there is too much anaylasis. If the animal is knocked down, who cares why it happens; it did.

 

[smokemaker]

OK, not being sarcastic, but theoretically if an 8 bore muzzleloader using a roundball generates 225 foot-pounds of free recoil energy, and you shoot a 200 pound deer, will the deer be knocked down?
Just thinkin' out loud