Energy Dump (rant)

[New_comer]

The bullet's energy is supposed to help it crush, slice, dice, and break up tissue to be effective.

If the slug merely slides and slithers effortlessly through tissue and skin, it'd only give the BG a couple of very large sweat pores - a dramatic display of firepower, resulting to a useless acupuncture.

Translating energy to tissue destruction to effect bleeding requires proper bullet design. But, basic assumptions must be accepted: as in flat-end projectiles crush more rather than slither thru, that larger diameter slugs have greater chances to strike vital tissue, that the deformed metal edges of the peeled jacket slice even more tissue adding to the injury and so on. So, if most of the available energy is converted to the crushing and cutting of tissue, chances are better that the BG will cease hostile activity.

But, if the handgun bullet could be propelled to such speed that even in its rounded form, it still could crush the tough tissues and arteries to effect bleeding by mere mass displacement and impulse, then hollow points would have seen the last of its days.

Until then, I'd always marvel at the spectacle of 'energy dump' of JHP's and exotic bullets stopping those fanatical gelatin and clay blocks.

 

[benEzra]

unless the temporary cavity made exceeds the elastic limit of the tissue, you are just moving the tissue aside, and its going to go back where it was afterwards. If the temporary cavity exceeds the tissue limit, then it just became the permanent cavity. If the temporary cavity is bigger than the tissue itself, this is just another variant of the temporary cavity exceeding the tissue limit.

Entirely true. The one thing that I think Fackler et al miss, however, is that tissue is a composite, and the elastic limit for one component of said tissue is different from that of other parts. Nerves, for example, are extremely fragile (ever bumped your elbow where the "funny bone" nerve passes through?) and their functional elastic limit is quite low at the microscopic level, whereas that of the connective tissue surrounding them is quite high. Dilated blood vessels are quite fragile (hence the danger of transecting your descending aorta by falling off a low roof and landing on your side), and it has been shown (Ragsdale et al., Armed Forces Institute of Pathology) that a pig aorta embedded in ballistic gelatin can be transected by the stretch cavity even if the surrounding gelatin is undamaged (i.e., outside the permanent cavity). Hence, a large temporary cavity can conceivably act to stun nerve ganglia, make muscles unusable (ever pulled a muscle? ever pulled one to twice its normal max length??), activate artery and arteriole stretch reflexes that cause a massive drop in blood pressure (by artery relaxation), and a whole host of other factors that could contribute to a "stop." Meanwhile, the large stretch cavity may allow a couple inches leeway in shot placement, in that a blood vessel just outside the permanent cavity might still be transected.

Assuming that you have an infinitesmally small bullet, say the size of an atom with the same energy as a 230gr bullet going at 880fps, aside from poking a small hole, and heating up some tissues, and maybe causing some individual cells DNA damage, the person is still going to be alive after being hit. Heck, hit them with a gazillion of these and maybe their hair will fall out after a week.

Actually, the lethal whole-body dose from gamma radiation, translated into joules, is the same order of magnitude as the KE of a handgun bullet.
500 rem = 500 rad (for gamma rays) = 5 J/kg body mass, so
75 kg person * 5 J/kg = 375 J = 277 ft-lb
(Fun fact for the day.)

 

[griz]

Well to get back to the original rant, comparing hunting bullets (rifles) to self defense bullets (handguns) is an apples to oranges comparison. Actually a closer analogy would be cantaloupes to oranges. For most game, rifles have energy to spare and can thus use the surplus to plow through the extra obstructions game animals present. Animals are usually horizontal and thus have shoulders and mid-sections that can get in the way, people are vertical and generally don’t have as much obstructing areas.

For a true comparison, look at FMJ pistol bullets versus JHP. For normal SD calibers, JHP bullets are acknowledged to be more effective than FMJ, even though the JHP may likely not exit. The effectiveness isn’t based on an exit wound, it’s on how much of the important equipment inside is torn up.