AFRICA HUNTER QUEST© 

Chapter 12 - THE GEEZER’S BULLET TESTING 

    GG:   I want to give you fair warning. What you have heard and will hear from me will be tough to validate from other sources. The majority of these sources are well-intended media types. From my literature research, it was obvious to me that most are writers that hunt, not scientists or engineers that hunt. At best, what they had to say about bullet terminal performance and bullet testing methods only furnished clues to the answers I was seeking. 

    As an engineer, I seek explanations and answers based on concepts grounded in the physical sciences and engineering mechanics. My conceptual explanations of how impact velocity affects hunting bullet performance are examples of this approach. 

    The bullet testing I am about to explain is concept-based with little to no apparent validation from others that I was able to identify. My methodology and subsequent interpretations could easily be classified anywhere from comprehensive to rubbish. Regardless, the testing and the results made sense to me, answered my questions, and served my individual purpose. What I have done may not have universal application for others. Take the best and leave the rest. 

    I think it’s important to emphasize what I am trying to model with the gel testing. Anyone who has ever done a red-neck autopsy on an animal dispatched with a high velocity cup and core bullet understands the tissue damage can be obscenely significant. The hole diameter made by the bullet is ridiculously small compared to the diameter of the blood-shot tissue that surrounds it. As such, I consider the disrupted, blood-shot tissue as part of the wound, and am including blood-shot tissue as an integral part of the wound cavity.  

    The blood vessels and capillaries within the blood-shot tissue have been ruptured and can weep blood at a far faster rate than undamaged tissue. The periphery of the blood-shot tissue is way greater than the periphery of the bullet hole. The greater surface area of the blood-shot tissue allows faster bleed-out from the surrounding, undisrupted tissue. In civil engineering terms, the wetted peripheral area of the blood-shot zone is vastly greater than the wetted peripheral area of the actual bullet hole, and thus allows for greater blood flow and volume that conceptually results in faster bleed-out. 

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    What I have just described is the basis and definition of what I am calling wound cavity volume: the total volume of tissue disrupted or destroyed due to passage of the bullet. That may not be in keeping with how Dr. Fackler or experts on physiology define it. But I believe that definition is compatible with how 20% synthetic gel reacts to passage of a high velocity hunting bullet, as I will subsequently describe. As I have previously stated, my analytical model assumes the radial extent of the fractures in the gel represents the radial extent of blood-shot tissue. 

    D:      Is 20% synthetic gel the same as FBI gel? 

    GG:   No. Not even close. It is way stronger and resists radial expansion and penetration to a much greater degree than FBI gel. 

    D:      (Smirking) Then it would seem to me that whatever test results you got are of no real value.  

    GG:   Spoken like a true absolutist and gel testing purist. You are absolutely correct in the sense that the results do not precisely model what happens in real tissue, likely cannot be rigorously linked by some conversion factor to analogous FBI gel results, and do not predict real world, in-the-animal bullet performance. No argument there.  

    GG fell silent and stared at the Pilgrim with a faint smile. “This is it,” thought GG. “A fundamental litmus test. The testing results and their relationship to generic bullets and impact velocity are fundamental for determining a responsive hunting problem solution. Either he asks the obvious question and we sit and talk for another hour or so, or the entire ‘Can my 270 Winchester and ammo be used to take a kudu’ dies in a pile. It’s up to him.” 

    Donny started back at GG. “Damn him,” thought Donny. “Another mind game. Totally rogue and bogus testing with no relevance to accepted norms. Undoubtedly pure mental masturbation. What was the point? …. Duh, what was the point . . . “ 

    D:   Then why did you do the testing? 

    “I guess we continue to march,” thought GG. 

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    GG: I wanted a convenient, consistent, and presumed conservative testing method to obtain wound cavity volumes and penetration lengths in order to compare various bullets.  

   Donny sat there transfixed. He couldn’t believe what he was allowing to happen. His tenacious, combative nature had goaded him into foolishly asking “why”. He was now the cobra summoned from the security and relative comfort of his terminal ballistics  basket by incomprehensible techno-noise with no identifiable pattern. Like the cobra, he was intrinsically poised to strike the noise purveyor to rid himself of his tormentor. But he couldn’t do it. He was somehow mesmerized by the audacity and potentially superficial logic of the Geezer’s spew. He couldn’t help himself. He had to know. 

    D:      So, what was your test setup and how many bullets did you test? 

   GG:   Each gel block was comprised of 20% synthetic gel. The gel was clear and allowed an unencumbered view of the bullet’s path through the block. Each block was 6x6 inches in section and 16 inches long.  I placed three blocks end-to-end to allow up to 48 inches of bullet penetration.  

   The blocks were supported by a structural lumber cradle resting on portable saw horses placed at 135 yards. Neglecting the distances at which my four springbok were taken, 135 yards is the average shot distances for 24 animals taken in three South Africa provinces. The cradle was spacious enough to allow each block to move independently in response to bullet impact, but kept them from falling to the ground. 

   Each block came furnished with a penetration calibration certificate referenced to NATO standards. Each block indicated a test penetration of 1.60 inches by a 0.177-inch BB fired at an impact velocity of 590 fps, all within the specified NATO penetration standard of from 1.25 to 1.70 inches. 

   Oehler P-35 chronograph screens were placed directly in front of the cradle to record bullet impact velocities into the gel. The initial, impacted surface of the front gel block was covered with an impala hide that averaged about 0.050 inches thick.  

   Each test bullet was weighed and measured to determine pretest weight and length. Weights were determined to the nearest 0.1 grain and lengths to the nearest 0.001 inch. 

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   Pictures of the blocks were obtained immediately after the bullet impact to visually record their orientation and displacement. The blocks were then reassembled into their test position, and further pictures were taken. Crude measurements were obtained of the bullet’s penetration length, length to apparent maximum cavity ‘diameter’, the maximum apparent cavity ‘diameter’, and the length of the cavity presumed to model the majority of blood-shot tissue. These measurements were taken with either a yardstick or carpenter’s tape measure, all to the nearest ½ inch. 

   The blocks were then placed in factory-furnished plastic bags and transported to the shop where they were reassembled and further pictures were taken. Refined measurements were taken to the nearest ¼ inch and served as a check/confirmation of the field measurements. Observations and measurements were recorded on formal data sheets prepared specifically for this testing. 

   The clear gel allowed critical observations of potential bullet tumbling. Tumbling was indicated by comparing final bullet orientation to the intended flight path as well as by any apparent dramatic changes in the extent of radial fractures in the gel. Limits of inferred tumbling were measured to the nearest ¼ inch and recorded on the data sheets. 

    Retained bullets were removed and their final weight was determined to the nearest 0.1 grain. Each bullet’s final length and both its maximum and minimum mushroom diameter were obtained to the nearest 0.001 inch. The bullet’s mushroom diameter is interpreted to be the average of these max and min diameters. Each bullet’s percent deformation, percent weight retained, and expansion ratio were calculated, then recorded on test-data sheets. 

    The bullet’s percent deformation can be interpreted as the percentage that each bullet compressed along its length due to impact stress. It answers the question “How much shorter is the bullet, as a percent, after the test?” 

    As I have already explained, the bullet’s expansion ratio is simply the average mushroom diameter of the expanded bullet divided by the bullet’s caliber diameter. This calculation result allows convenient comparisons among multi-caliber bullets. 

    I tested a total of 11 bullets: one in .375-caliber, five in 35-caliber, and five in 30-caliber. By my definitions, I interpret there are five generic types of expanding bullets used for hunting, and I tested four types.  

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    Some folks could rightfully argue that what I have concluded from this testing is bogus simply because my sample populations are so small. This testing was for my use, so I don’t really care. However, once I began interpreting the test results, they told a story consistent with my engineering expectations and assessments of the generic bullets’ designs.  

    The data reasonably portrayed what I expected, given the limited and very basic knowledge I claim to have about bullet terminal performance. Bullets universally acknowledged to penetrate, penetrated like gangbusters. Bullets universally acknowledged to expand, expanded like gangbusters. So much for confirming what everybody knew to be the obvious. That, in and of itself, could have been sufficient to claim victory. But, as you have already discovered, I have almost a death wish to fix what everybody claims ain’t broke. The test results led me to believe the cavities and penetration lengths obtained in the gel blocks were related to each bullet’s generic design. 

    I started with the 35-caliber bullets. One of the first bullets I tested was a 225-grainer with a reputation of being a penetrator. The next bullet I tested was a 225-grainer with a reputation of being an expander. I took pictures of these cavities and visually compared them side-by-side. The shapes were obviously different. The 35-caliber bullet that was supposed to be a penetrator had a cavity shaped like an anemic guppy trying to become an eel-snake. The 35-caliber bullet that was supposed to be an expander had a cavity shaped like a healthy guppy. The calculated total wound cavity volume for the expander bullet was actually slightly higher than for the penetrator bullet, even though the penetrator bullet had almost double the penetration length. Both 35-caliber bullets had impacted the gel at the same 135-yard distance. There was only 63 fps difference in impact velocity. What do you think is responsible for the radically different shapes and penetration lengths?  

    D:      Bullet design. 

    GG:   Yep. Bullet design. Premeditated design features and materials with each bullet had gotten one to penetrate like gangbusters and the other to expand like gangbusters, with apparently token homage paid to each bullet’s complimentary terminal performance component. In my mind, neither bullet could be considered to have terminal performance balanced between wound cavity volume and penetration. Questions begged to be asked concerning what bullet design features did what, and how that resulted in those shapes, dimensions, and volumes.  

    D:      (Smirking) You wonked out, didn’t you? 

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    GG:   You betcha! I discovered that design features conceptually and logically controlled both the rate and extent of a particular bullet’s deformation. That combination of deformations resulted in cavity shapes, dimensions, and volumes that made conceptual sense, at least to me. That understanding allowed me to qualitatively predict how one particular 35-caliber bullet would perform based on modifying it two different ways.  

    D:      Qualitatively predict performance? 

    GG:   How the modifications would change the wound cavity volume and penetration length. 

    D:      (Again smirking) You didn’t stop there, did you? 

    GG:   Are you kidding?!! The magnitudes of the results I was getting and the success of qualitatively predicting gel test outcome gave me enough confidence that I turned the testing into a contest. I tested bullets shot from three different chamberings: a 375 H&H, a 358 Winchester, and a 300 Winchester. The contest results would determine if bullets shot from either the 300 Winchester or the 358 Winchester could dethrone the consensus champion 375 H&H and its preferred bullet as the presumed ‘best’ chambering-bullet combination for hunting Africa plains game. The gel test results of my preferred .375-caliber, 300-grainer would be the standard by which the 30- and 35-caliber bullets were compared. 

    The results were surprising. Honestly, unexpected. At the end of the day, they made sense and I accepted the contest results as legitimate. 

    Donny couldn’t help himself. The old coot had taken a long walk off a short pier and drowned himself in numbers obtained from mad science rogue testing. The snark he had been loading throughout the morning’s conversation masked the lesson he told himself he had learned. 

    D:      (Big smirk) So, old-school big and slow got its a$$ whupped!! 

    GG just sat and stared at the insolent little $#!+. Up until then he felt he had successfully ignored the youngun’s smirking and mocking tone. He now tried his best to keep his face neutral, expressionless. Maybe he did, maybe he didn’t. He was gratified he had made the attempt. There was a time not so long ago when his reaction would have been different. Some could testify well beyond way different.  

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    He certainly didn’t have to subject himself to any of this. He was donating his time more than any documented or ‘accepted’ knowledge. Most so-called knowledge was typically incomplete at best, suspect or down-right bogus at worst. Regardless, knowledge evolved accordingly. Time was finite, absolute in its definition and reality. GG now considered time as a commodity. Its allocation was precious and commanded compensation far higher than what was being offered by the Pilgrim. Just what was he donating his time for? 

    The youngun had the right stuff to assimilate the content being dispensed and arrive at a reasonable answer to his self-imposed dilemma. But his attitude sucked. Snark was embedded in his stubborn nature. Snark could damn-well prevent him from achieving the ‘reasonable’ part of his answer. Snark prevented him from recognizing when chicken salad wasn’t chicken $#!+. Yet . . .  

    Again, GG took a chance. 

    GG:   Nope.  

    Donny sat and contemplated the several-second pause in GG’s response. The Old Man’s face really gave no visual clue for the potential reason. Maybe he had done stepped in it with his comment, maybe not. 

    D:      So, what happened? 

    GG continued to eye the youngun. “He doesn’t know he stepped in it,” thought GG. “I can sure-as-hell relate to that. I wonder if the little twit actually cares?” 

    Donny noted the Old Man was not forthcoming with a reply to his question. The Geezer had seemed stoked enough about the testing that he expected an immediate response. “Whatever,” thought Donny. 

    GG:   I concluded my gel testing approach was a relevant method to predict, assess, and quantitatively compare the terminal performance from any chambering- and-bullet combination. Furthermore, I had taken 11 animals with the 300 grainer and had a reasonable expectation of its field performance. I therefore concluded its gel test results could be used to assess and likely predict the general field performance of the other bullets, based on their gel test results. 

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    D:      (Still smirking) Even though you didn’t use FBI gel. It can’t be legitimate. 

    GG:   The operative words are quantitatively compare. Does anybody, even the FBI, use ordinance gel to measure anything other than penetration length, mushroom diameter, and retained weight of the bullet? That is a quantitative comparison, sure enough. But what about the wound cavity, one of the actual focal points of Dr. Fackler’s evaluations? Where is that quantitative comparison? Measuring the actual wound cavity volume could very well cause real experts, not hacks like me, to conclude that a bullet’s weight retained and mushroom diameter are actually sidebar issues of no real relevance. 

    The Feds wanted a test medium compatible with human tissue. I speculate the objectives were to retain pistol bullets of the day for both crime analysis and penetration measurements. The cavity produced apparently seemed to be nothing more than a ‘gee whiz, look at that’ feature. I would be thrilled if someone with legitimate credentials would explain how or if the cavity was measured and how that measurement was used in any ballistic terminal performance evaluations. I would love to be told the error of my testing and analysis ways so I could actually learn something. 

    I’m tired of this wound cavity volume subject potentially being treated as a ‘need to know’ basis. Damn it, I need to know. 

    Why? Because hunting bullets are different. Double to triple the impact velocity of pistol bullets? I don’t know, I’m not a pistolero. Compared to pistol bullets, hunting bullets explode. Effective penetration rather than total penetration becomes the issue in order to answer the question “Will the likely wound cavity explosion occur in the boiler room?” If it does, what is the magnitude of the explosion in terms of actual cavity volume? 

    In the context of both effective penetration and modeling real-world, big-game hunting, does FBI ordinance gel accurately simulate/represent a cape buffalo’s shoulder muscle? Somebody is gonna have to show me actual test data that say it does. Right now, my supposedly suspect logic says no, bordering on hell no. 

    All of this can be written off as crackpot, esoteric babbling, but only if folks who can be considered authoritative share any kind of quantitative wound cavity volume test results from their gel testing. The FBI doesn’t. The military doesn’t. The manufacturers don’t. This is going to sound harsh, but the manufacturers’ ‘gee

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whiz’, slow-mo videos of ordinance gel doing the hully-gully upon bullet impact are meaningless. All high velocity hunting bullets make ordinance gel do the hully-gully in slow motion upon impact. Tell me how far the bullet penetrated. Show me the cavity measurements and volume determinations. Show me the retained bullet. If folks must, chant retained weight and mushroom diameter. Do it all over again with the same bullet at a different impact velocity. Show me tables of data for each bullet. Show me graphs of data to identify trends and relationships based on impact velocity for a particular bullet. Tell me what the sweet-spot impact velocity range is. Then do it all over again for a bullet in the product line that has a different generic design. Why? Because I’m trying to decide what bullet would be the most effective for taking a kudu with my 358 Winchester on a rear quartering shot based on my particular hunting scenario, my terminal performance requirements, and my tolerance for risk. 

    Donny sat there wide-eyed. Damned if he hadn’t done it again. Not only had he been unwilling to listen, he had substituted opinion for fact. The Old Man would not stand for either. The Geezer had been locked and loaded, then peppered his juvenile, brain-dead a$$ with intellectual birdshot. He quickly adopted an awkward and uncomfortable fallback position, armed only with a three-letter word. 

    D:      So, why did you choose to do this testing with 20% synthetic gel? 

    GG:   Lots of reasons. First, its physical properties don’t significantly change with changes in temperature. That makes storage, transportation, and data acquisition way easier. Furthermore, there is more confidence in being able to replicate the magnitude of the measured data. The gel blocks come furnished with a calibration certificate referenced to NATO standards. FBI ordinance gel has none of these benefits.  

    Second, the synthetic gel blocks I used are clear so you can be sure of what you are seeing. That helps in formulating concepts and conclusions based on the actual test data. Ordinance gel is kindly translucent to opaque, potentially obscuring terminal performance indicators.  

    All that is well and good, but there are field and testing-reality reasons why I selected 20% synthetic gel. First, it is way stouter than FBI ordinance gel, offering considerably more resistance to penetration from a rifle bullet. That is an important consideration because I am beyond skeptical that FBI ordinance gel accurately simulates animal shoulder tissue. Furthermore, that higher resistance to penetration reduces the total number of blocks required to actually capture the bullet in order to

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measure the total penetration length. That and a shorter test length improve the portability of the blocks’ support apparatus that I had to tote around. Finally, passage of a bullet produces shape and fracture patterns of the wound cavity similar to the ones obtained with FBI ordinance gel. 

    D:      Fracture pattern? 

    GG:   Cracks or tears. I believe the radial limits of the fracture pattern models the actual radial limits of the inferred wound cavity. Whether the cavity is shaped like a blowfish, guppy, or eel-snake, the actual cavity shape is defined by the crack or tear limits that radiate outward from the bullet’s trajectory as it penetrates through the gel. Multiple cracks form, all radiating away at a 90-degree angle from the path of the bullet. I’m calling these cracks fractures. The gel is not soft enough nor elastic enough to allow the simple formation of what you and I would call a bullet hole as a bullet passes through. It splits like yellow pine occasionally does when you try to hammer in a 16d nail. 

   The 20% synthetic gel is considerably stronger than the FBI ordinance gel. As such, I speculate the radial extent of the fractures produced in the 20% gel is considerably less than in the ordinance gel. The actual hole formed by the bullet in either gel is very small compared to the bullet’s original diameter, and certainly not even close to a mushroomed bullet’s diameter. The actual hole I got with even a mushroomed .375-caliber bullet was little bigger than the diameter of a stitching needle. In either case, there is no direct method to measure the actual volume of the cavity. 

    D:      (Again smirking) And I suppose you have come up with one. 

    GG did his best to ignore the ‘return of the snark’. It was a bad sequel to a bad movie. He lied to himself by claiming the youngun’s comment was really in the form of a question. 

    GG:   Direct, no. Indirect, yes. Fundamentally easy. Operationally, a pain. 

    D:      You say the fractures in 20% synthetic gel are of lesser extent than the ones in FBI ordinance gel. Then I don’t see the point. Whatever you are measuring, indirectly or not, has no basis in reality. 

    GG:   Basis in reality? If you choose to be an absolutist and will entertain no test method that does not produce a direct connect to an actual real-world result, then

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yes. If you apply your basis in reality constraint to FBI gel test results, there is no reality because gel doesn’t turn into the real-world goo of blood-shot tissue. But if you choose to believe that a test method reasonably models the concepts and mechanisms that are embedded in the real thing, the test results in 20% synthetic gel can be an issue of scale. 

    I am not interested in an absolutist’s testing method and am only mildly interested in a scaler’s testing method. Why should I be interested in either? What is the benefit or necessity of providing either a direct link or scaler link between my data and data no one is willing to share, let alone explain? 

    The true benefit of a test method that reasonably models the concepts and mechanisms embedded in the real thing is that it allows representative comparisons of those test results. That can be more than enough. If you add in the test result that you believe is the standard by which all the other test results are to be compared, in this case my 300-grainer, you then have an excellent basis for an informed comparison and choice. The fundamental question then becomes: “Do I believe testing a bullet in 20% synthetic gel reasonably models the concepts and mechanisms embedded with testing in FBI ordinance gel?” My answer is an unequivocable “yes.” My reality link is the known field performance of my 300-grainer, the test result standard by which all the bullet competitors’ test results were judged. 

    GG watched the youngun. He knew the kid wanted to play the BS card so bad he could almost see his hand involuntarily twitch. Time for another litmus test, although the youngun would interpret it as an invitation to a trial by combat. That was the point. 

    GG:   Care to know what that indirect volume measurement technique is? 

    “Damn him,”, thought Donny. 

    D:      I suppose. 

    GG:   The first step is to slice the gel block into wafers of a convenient thickness. The typical thickness I used was ½-inch. I used a dial caliper to measure the maximum and minimum extent of the fractures on the bullet’s exit side of the wafer. In effect, I was measuring the fracture pattern’s maximum and minimum diameter. I averaged the two measurements. I did that for all ½-inch thick wafers.  

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    What I did next was calculate the volume by a technique known as the average end area method. This technique is routinely used by both civil engineers and grading contractors to compute earthwork cut and fill volumes. 

    Because I had determined the average diameter of the fractures for each wafer, I could then compute the average circular area for each in square inches. Then I took the average area of two adjacent wafers and multiplied that average by ½ inch. The answer is the volume created by the fracture array for a particular wafer pair. The fracture volumes for the wafer pairs are then summed to get the total volume. 

    Donny rolled his eyes. “Geeze Louise!!” thought Donny. “I knew it! It was nothing more than another numbers’ torture exercise! I can almost hear the old coot screaming at them to confess.” 

    GG watched the Pilgrim squirm. He knew the youngun was close to mashing the ‘shut down’ button. 

    GG:   You would have to see the process for yourself and crank your own numbers to validate what I have just told you. But I can assure you it is nothing more than simple applied geometry and arithmetic.  

    D:      Has anybody done this before? 

    GG:   A media-type that does considerable bullet testing and is privy to ‘manufacturer think’ has written that determining wound cavity volume in ordinance gel or synthetic gel is not possible. So, I’m pretty sure the answer is no. 

    D:      Sir, all I can say is you have obviously taken a walk on the wild side, maybe even gone on a trip and never left the shop. 

    GG:   (Grinning like a Cheshire cat) But it gets better. 

    D:      Better?!! 

    GG:   Yep. Way better. I conjured seven different metrics or measuring sticks to evaluate the wound cavity: three based on penetration length; one based on diameter; two based on volume; and one that is a calculation using measured test data that attempts to judge each bullet’s potential for producing hydrodynamic shock. 

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    Donnie audibly groaned. This was insane. Surreal. The Geezer was talking in tongues. Donny didn’t know why, but he tried to reel back a conversation whose orbit had spiraled horribly beyond his or anyone’s known reality. 

    D:   (Obviously agitated and frustrated) You say you measured each bullet’s retained weight and mushroom diameter. Did you use any of that to determine the final bullet rankings?  

    Donny saw the Old Man’s facial expression transform into that stupid Dr. Evil grin just before he announced he was going to ransom the world for a million dollars. 

    GG:   Nope. That’s the best part. Didn’t need to. Each test bullet’s percent deformation and the mushroom symmetry or roundness were useful in explaining trends and variations of the wound cavities and penetration lengths. But those seven parameters were the basis for the rankings. 

    Donny’s eyes partially glazed over. At the start of this conversation, he sensed that GG had figuratively placed the terminal performance equivalent of Pandora’s box directly in front of him. With each series of questions, the box seemed to have been pushed closer. It was now figuratively within reach. With each incremental push, the Geezer seemed to be challenging him to open it, with the challenges becoming more obvious with each push. The last push was nothing short of baiting him. “How bad do I really want to know if my 270 Winchester and ammo are okay to take a kudu?” 

    D:      So how is all this related to generic bullet design? 

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