The Poor Man's Hollow Point

[Rich/WIS]

After WWI the Brits switched from the 455 to the 38 S&W with a 200 grain bullet at about 700fps. They decided that it was as effective as the 455 and its use during WWII proved them right. The bullet at that weight and velocity was unstable and tumbled. Believe I read this in one of Barnes' Cartridges of the World. Only serious handgun I own is SA 1911A1 Range Officer and all I shoot is 190 grain SWC at about 725-750 fps, and in an emergency guess it will have to make do.

[tazman]

I can't think that a properly placed 190 grain slug moving at 750fps would fail to do the job.

[rintinglen]

After WWI the Brits switched from the 455 to the 38 S&W with a 200 grain bullet at about 700fps. They decided that it was as effective as the 455 and its use during WWII proved them right. The bullet at that weight and velocity was unstable and tumbled. Believe I read this in one of Barnes' Cartridges of the World. Only serious handgun I own is SA 1911A1 Range Officer and all I shoot is 190 grain SWC at about 725-750 fps, and in an emergency guess it will have to make do.

This one of the myths that keeps getting recycled and ought to be put to rest. The British may have believed that a 200 grain bullet at 700 fps might be the same, but the reality was that first, the heavy bullet 38 ran closer to 600 fps than 700, and it did not work particularly well. I formerly had the acquaintance of an expatriate South African Police officer who had nothing but contempt for the 38 Revolver, Mk I. He recounted an adventure wherein a heavy leather coat sufficed to prevent death or serious injury to the malefactor, while in another encounter, a burglar shot five times out ran the two police officers trying to capture him.

[Piedmont]

The 200 gr. .38 S&W load wasn't even standard issue by the time WWII rolled around. Britain had gone to a 178 gr. pointier round nose jacketed round. Whether it was effective I would sure like to know but haven't found anything I consider reliable saying it was.

[35remington]

Louisiana Man, a member here, went to some lengths proving that heavy clothing was not at all an impediment to a 200 grain 38 moving at 600 fps. Its level of effectiveness may be debatable compared to alternatives but penetration on heavily clothed people was not an issue.

Suggest doing a search.

[35remington]

Here ya go.

http://castboolits.gunloads.com/show...t-200g-bullets

[Old School Big Bore]

I guess I've spent too much time on Farce-Bukk because every time I read a post by Outpost75 or 9.3X62AL, I catch myself looking for a 'like' button...
Sorry for the divergence from the OP but in reference to two-boolit loads: In my own tandem-boolit loading, mostly 44s, after being influenced by Grennell and Nonte, I used some Speer swaged .433 balls run through a .429 sizer with a WC top punch, which gave them a fairly wide 'belt' around their middles and slightly flattened tops & bottoms. I put a little disc of lube between them. Then I found a Lee single cavity 44-120-WC mould and stacked two of those.
That idea won me a lot of bets until the other guys caught on. The jerks who were the Department 'range guys' were in the habit of suckering new officers into betting a case of beer on their qual scores and although they didn't manage to sting me, I despised the way they took advantage of most of the rookies and decided they needed a comeuppance. One of them had a compact Beretta 92, and all his magazines were 10-rounders. I bet him five cases of beer that my M29 could put a total of 12 holes in two edge-to-edge B27s at ten yards before his 92. He jumped on it. We set up 4 B27s and had his buddy call the fire. When I was getting set up, I put six empties in an HKS speedloader in a pouch. When we got the whistle, I put three of my doubles in the left silhouette, lowered the 29 for two seconds, put the other three in the right silhouette, and ejected my empties and the six extras at my feet. I expected to hear, hey you only shot six times, but the 9mm firing disguised my shots. I was ready to claim each shot was a double tap. The hotshot was loading his second magazine when I reholstered and raised my hands. They came and looked at my pile of brass and empty speedloader on the ground, shrugged and the next day I had five cases of beer. I gave it all to several of the rookies they had suckered.
That double 120 at about 1200 was in my estimation the equivalent of a double-tap of pre-expanded 9mm 120 grain boolits. I still have the mould and 100 of its boolits lubed and ready to load, and two boxes loaded, single boolits over 4.0/red dot in .44 SPL brass. I think I'll see how the new-to-me 624 likes 'em.

[pettypace]

Here's one that seems to be a pretty reliable tumbler:

Attachment 249246

This block of gelatin was actually the second of two ammo can size blocks. So these five slugs had already penetrated 11" of gel before entering this block from the left. The actual penetrations were something like 12", 13", 14", 14", and 16". All five bullets tumbled. That is, they did a 180 degree flip ending up base forward.

The bullets are about 207 grains, hard cast from a SAECO mould, seated just deep enough to clear the barrel, over an adequate charge of Herco, and fired from a 4" .38 S&W Regulation Police revolver. I didn't have a chronograph at the time, but I would guess the velocity was close to 600 ft/s -- about the same as the Webley 38/200 or the original .38 S&W Super Police load.

It's worth considering what, if anything, the "tumbling" might actually contribute to the bullet's effectiveness for civilian self defense. First, even at a lazy 600 ft/s, a 207 grain .36 caliber projectile that flies point on would likely penetrate close to 30" of 10% ballistic gel. In that case, it would probably be just about as effective as any other over-penetrating .36 caliber projectile, say 9mm hardball. But apparently the tumbling takes a lot of the steam out of a bullet and transfers it to the target.

That makes sense. It takes some time and distance in the gel for that long bullet to do its 180 degree flip. And during that time and over that distance, the bullet presents a much bigger cross-sectional area to the gel. It's as though the bullet actually had a bigger "effective diameter" than .36 caliber. But how much bigger? We can use the "expedient equation" (from Quantitative Ammunition Selection by Charles Schwartz) to estimate this "effective diameter."

Here's the Schwartz calculation for the penetration of a 207 grain .36 caliber truncated cone at 600 ft/s:

600^0.72*207/7000/(0.36/2)^2/3.14

If you cut and paste that mess of numbers and symbols into a google search, google will return an answer of just over 29 inches of penetration. (As near as I can interpolate, this agrees almost exactly with the graph for truncated cone penetration in Duncan MacPherson's book Bullet Penetration.)

But the bullets that tumbled in the gel block above only penetrated an average of about 14". Suppose now, with that calculation still sitting in the google search box, we just change the 0.36 bullet diameter to something bigger -- say 0.50 -- and let google search for that answer.

So, google says that a 207 grain .50 caliber truncated cone bullet at 600 ft/s would penetrate about 15". And if I try again with a diameter of .52 caliber, I get pretty close to the average of 14" of penetration.

My guess is that the tumbling bullets in the picture above would be just about as effective as any .38 caliber jacketed hollow point bullet that expanded to about 0.52" and penetrated to about 14" in 10% ballistic gel. If so, that's not bad for the little .38 Short & Weak.

[pettypace]

A question, if you don't mind...

Are the 207-grain bullets that you are modeling better described as having a round nose profile or are they more of a flat nosed/truncated cone profile? Their shape is somewhat obscured by the clouded gelatin material. They look more like round nosed bullets to these old eyes....

Hard to tell from the photo, but those are flat nosed bullets out of a SAECO #351 mould. As for the exponent, I agree -- 0.735 is probably closer. So that would give an effective diameter of 0.54" with an average penetration of 14".

Of course, all that assumes it makes sense to talk about an "effective diameter" for a bullet that does a 180 degree flip in the target.

[pettypace]

...

Modeling variable attitude lateral flow past cylinders (CFD) is extremely complex. For example, at R_e = 1,000, the attached boundary layer on the cylinder is laminar. The boundary layer separates at approximately 82° and the wake is turbulent. Using a turbulence model makes the boundary layer separation point move to the down-flow (rear) side (>90°) of the cylinder. So, this means that it is not correct to employ a turbulence model like K-epsilon to compute the flow. Doing so results in a modeled wake that is much narrower than it is in actuality, which means that the drag is also less than it is in actuality. In testing, the separation point does not move to the rear side of the cylinder until much higher Reynolds numbers (about R_e = 250,000) prevail. At R_e > 250,000 , "drag crisis" sets in; boundary layer transitions occur and the boundary layer becomes turbulent.

Although I can see that mathematical modeling of a tumbling bullet is complex, I'm afraid your explanation is well above my pay grade. But what are we trying to model anyway? In this case, there's no need to model for the penetration -- we can just measure that. But the question remains, "How useful might these tumbling bullets be for close quarters civilian self defense?" The idea of "effective diameter" can be fairly criticized as simplistic or justly praised for simplicity. Either way, if it promotes discussion it will have served its purpose.

[35remington]

One would have to presume that if penetration was attenuated to this degree the wound track showed early tumbling. The only thing to resolve would be whether the same profile would reliably develop when used for real.

Might take a while to find enough reluctant volunteers.

[Michael J. Spangler]

In a nutshell, fluid flow-fields around tumbling bullets are extremely complex to model and, as velocity increases turbulence (chaotic, stochastic flow) does so too. Trying to do it by hand (say, on a Texas Instruments calculator) would be impractical and time-consuming at best. For a task like that, CFD (computational fluid dynamics) software like ANSYS CFX would be needed to process the differential equations needed to model flows like that.



Besides penetration depth, there are other physical parameters that merit examination and quantification. I'd respectfully offer that permanent wound cavity volume, pulverized tissue mass, and instantaneous/exit velocity are among them.



I agree. With physical gelatin models that are the dynamic equivalent of soft tissue, measurement of maximum penetration depth is easy enough and one of the attributes that makes those mediums (namely, 10% ordnance gelatin) so attractive. It is widely accepted that tumbling increases effectiveness, but putting a "hard" number in that is impossible. At the risk of opening the proverbial "can of worms", the Bio-Physics Division of the US Army Ballistic Research Laboratory at Aberdeen Proving Grounds (BRL) produced a mathematically-based predictive personnel incapacitation equation based upon 7,898 wound data accumulated by the WDMET (Wound Data Munitions Effectiveness Team) during the Vietnam War. The US Army personnel incapacitation equation relies upon an incremental kinetic energy expenditure parameter (ΔE₁₅) of a random munition strike to the center of mass (COM) of a combatant’s or assailant’s body over a penetration depth of 1 – 15 centimeters to predict a projectile’s probability of incapacitation, represented symbolically as P_[I/H]. Greater values of ΔE₁₅ equate to greater strain energy storage within surrounding tissues produced by the bullet’s passage through them. Increased strain energy storage increases the likelihood of proximate tissue damage and with that damage, an increased probability of incapacitation. Of course, there are a few individuals in the terminal ballistics research community who dispute the model's validity, but the US Army relies on these P_[I/H] models even to this day in their ORCA (Operational Requirement-based Casualty Assessment) computer code which still contains the BRL P_[I/H] model as its ballistic insult subroutine MUVES-S2 (Multiple UNIX-based Vulnerability Estimation Suite). MUVES-S2 is embedded in ORCA and is used to evaluate the vulnerability/lethality of munitions in terms of injury to personnel within target geometry. The ORCA and MUVES-S2 vulnerabity code has been reviewed by peers in the medical and biological fields and by the U.S. Army and Navy and found to be adequate in producing injury, impairment, and operational casualty assessments. For that reason, I prefer to use the BRL P_[I/H] model as a measure of lethality within its documented limitations. I am not insisting that anyone here accept the BRL P_[I/H] model without doing research of their own; that responsibility is up to each one of us.

Your use of "effective diameter" to address the phenomena of tumbling, while admitted "simplistic", is probably the best "guess" that we can make without bringing expensive multi-physics software suites to the table. Given the magnitude of uncertainty and variation that is seen with yawing/tumbling bullets, it is probably as accurate of a representation as we'll ever see of the phenomena without getting lost in the minutæ that would inevitably be required.

In the end, "how useful" tumbling bullets might be for close-quarters civilian self-defense is going to be a "one-for-one" proposition. Given the nearly infinite variability of the human body, every single event will be a law unto itself.

You stole the words right out of my mouth

[pettypace]

The US Army personnel incapacitation equation relies upon an incremental kinetic energy expenditure parameter (ΔE₁₅) of a random munition strike to the center of mass (COM) of a combatant’s or assailant’s body over a penetration depth of 1 – 15 centimeters to predict a projectile’s probability of incapacitation, represented symbolically as P_[I/H]. Greater values of ΔE₁₅ equate to greater strain energy storage within surrounding tissues produced by the bullet’s passage through them. Increased strain energy storage increases the likelihood of proximate tissue damage and with that damage, an increased probability of incapacitation.

I'm sure there's a lot more in that can of worms, but focusing on the first 15 cm (6") of penetration sounds like a dangerously bad idea to me.

Here's Fackler's wound profile for the .357 Magnum Glasser Safety Slug:

Attachment 249560

The KE dump in the first 15 cm for the Glasser is about 566 ft-lbs -- about twice the ΔE₁₅ of the fully expanding 230 grain JHP .45 ACP used as an example of the BRL model in Quantitative Ammunition Selection. Yet, despite having twice the ΔE₁₅ of the .45 JHP, as Fackler notes, "Most of the human body's vital organs lie at a penetration distance deeper than the Glasser can reach."

[Outpost75]

Schwartz,

By any chance did you work in CSTA at APG in the early 1980s?

I worked on some projects brought in by Det "O" with Dr. Robt. L. McCoy at BRL on the AK-74 and 5.45mm ammo evals about that time and we may have crossed paths?

[Michael J. Spangler]

Funniest post of the thread!

I can't keep up with the technical stuff at this rate so I figured I would add in some comic relief

[Michael J. Spangler]

Well, Mike, you did just fine. Thanks for the humor. It was the "bright spot" to an otherwise tough day.

I'm happy to hear it. Sometimes it's the little things that can lift the weight after a long week.

Thanks for joining in on the conversation. I really fell in love the the IWBA articles and the knowledge in this thread is a breath of fresh air compared to the local gun forum I'm on.