Shooting Holes in Wounding Theories:

3. A Study of Sectional Density

In a stunning repudiation of conventional wisdom, the lightest bullet tested penetrated to the greatest depth and the heaviest bullet lost the most mass both in absolute terms and on a percentage basis. To be fair, apart from the 200 grain Speer, the bullets performed as one might expect (see the Figure below). Still the point I raise remains valid: generalizations are simply that; specific bullets may not behave as expected.

The best looking recovered bullet was the 225 gr Speer boat-tail, faring far better than the more famous Sierra Game King which suffered a core separation and an asymmetric folding back of the jacket. This latter feature I consider to be a serious flaw because it suggests inconsistency of behavior (and this at a high impact velocity where things ought to be certain). I was amazed at the behavior of the big 275 gr semi-spitzer. This bullet has a sectional density of .344 ­ thats the same as a 500 gr bullet of .458 caliber. If anything, this should be the one to drive like a runaway freight train. At a lower velocity it might, but it expanded more violently than the others (probably due in part to the generous amount of exposed lead in the tip). The wound cavity created can only be described as cavernous. Its not a bad bullet by any means, but no more effective (at this velocity) against tough heavy animals than the little 200 gr Speer, which performed very respectably considering that its an ordinary inexpensive design.

Criticisms with this study might include the high velocity selected. Its true that at lower velocities the semi-spitzer would not have come apart like it did, but presumably the little 200 gr and the 225 gr boat-tail would also perform better. I question whether the 250 gr Game King would even function at an impact velocity below 2200 fps (this is a bullet design that would profit from a serrated jacket and/or a polymer tip insert). One might object to my attempt to remove the variable of velocity. I suspect that the 200 gr bullet loaded to its full muzzle velocity of 3200 fps would probably penetrate about 12 inches and lose 65% of its mass. This test corresponds to a range of about 175 yds in the .340 Weatherby but roughly the muzzle velocity from a .338-06 chambering. I wanted the test to be hard on the bullets because under those conditions differences should be most evident, but I feel that this range reasonably covers practical engagement conditions as well.

These small-bore bullets in the 7mm-08 Remington and 7 mm Remington Magnum taken as a whole grossly substantiate the conventional wisdom regarding sectional density. However, I call attention to the (rarely acknowledged) fact that the bullets of lowest sectional density are normally driven to the highest velocities while those of high sectional density are driven to the lowest velocities. Thus we have strongly mitigating factors which may account entirely in some cases for the observed differences. Notice how much smaller the cavities are than for the medium bore bullets (see the Figure).

The little 130 grain boat-tail spitzer is the lightest big game bullet that Speer recommends in 7 mm caliber. It produces a perfectly satisfactory wound for lighter big game taken under typical frontal shot angles, lacking only in deep penetration. The 140 grain Nosler is the old discontinued Solid Base style. It differs significantly from the newer Ballistic Tip only in the polycarbonate tip insert. However, the behavior of the 140 gr Ballistic Tip is quite different. Although I have been satisfied in the field performance, the Ballistic Tip is more prone to failures owing to the tip separation event and the uneven stresses this induces. The 150 grain Combined Technologies Ballistic Silvertip tested here experienced a complete core separation, the jacket deviating from the main path after 227 mm (8.94 in) and a tiny remnant of the core coming to rest at 282 mm (11.1 in). In a previous test the bullet passed too close to the unyielding table surface and the entire core literally squirted out like toothpaste leaving behind a husk of the almost intact and unexpanded jacket. The penetration was very shallow. In contrast, the Nosler 150 grain Ballistic Tip performed in a very restrained manner. Since there is presumably no difference in these bullets other than the black oxide coating, the variability is surprising.

The 154 grain Remington Extended Range Flat Base (ER-FB) Core-Lokt bullet is no longer manufactured and it is a tragedy. This is (was) my favorite 7 mm bullet and its a very reliable killer. It compares quite favorably with the 150 gr Swift Scirocco illustrated in the next section. The Speer 160 grain boat-tail spitzer does not produce either a larger diameter or a deeper wound than either the 140 grain Nosler or 154 grain Remington, demonstrating again that generalizations regarding sectional density are not meaningful when applied to specific bullets. The 175 gr. Hornady Interlock bullet performed very well despite its low velocity. My brother used this bullet in the 2000 season and got excellent exit wounds and blood (which was unnecessary since one deer dropped in its tracks and the other went only 35 yards). He also got incredible accuracy. Old fashioned bullets still work! Most shocking, the 175 grain Remington Core-Lokt stopped short of the penetration of the tiny 130 grain pill at very nearly the same impact velocity.

Legend - (L-R) Some of the .284 caliber bullets compared: (1) 140 gr Nosler Solid Base (discontinued), (2) 145 gr Speer Grand Slam (described in the next section), (3) 154 gr Remington Core-Lokt Extended Range Flat Base (discontinued), (4) 160 gr Speer boat-tail (not a Hot-Cor bullet!), (5) 175 gr Hornady Interlock

4. Small-Bore Bullets

The following Table and Figure detail the performance of several premium small bore bullet designs in a variety of weights.

For the first time I have a selection of the newest monolithic and all copper alloy bullets in a small caliber for examination. Impressive claims have been made about the performance of each of these designs. At present, for all but the X-Bullet I have only the test results to judge them by, no field experience (Since my safari in May of 2001, I can attest to the one-shot effectiveness of the .308-200 gr X-Bullet on wildebeest, hartebeest, gemsbok, and kudu ­ all large and tenacious animals ­ as well as on springbok and warthog).

Legend - (L-R) The monolithics in .284 caliber bullets (unfired and recovered): (1, 2) 120 gr GS Custom HV, (3, 4) 140 gr Barnes X-Bullet, (5, 6) 140 gr Lost River Ballistics J36

Perhaps the most innovative of these new monolithic designs is South African Gerard Schultz's GS Custom HV (for High Velocity). This is an evolutionary development of his earlier hollow-pointed HP design, which resembles an X-Bullet in form and function. Gerard turns these bullets from pure copper rod stock for precision. The most innovative aspect of their design is the series of ridges on the bearing surface, resembling the lube grooves on a cast bullet (though much shallower). The body of the bullet is designed to ride on the lands, with only the ridges filling the grooves of the rifling, thus significantly reducing resistance. The bullets are also designed with a high ballistic coefficient. The design theory is a tough bullet that will perform very efficiently with its kinetic energy, wasting relatively little on its own deformation, and retaining more downrange than substantially heavier bullets due to its high muzzle velocity and high BC. It was definitely efficient, penetrating as deeply as a 175 grain Nosler Partition. The "wound" made was similar to that of an X-Bullet, except that after about 240 mm of travel the long bullet shank yawed and left a "keyhole" shaped lesion in the wet paper (I have illustrated the maximum dimension, in the orthogonal view it would be the diameter of the narrow part immediately in front of the widening). The impact velocity is quite high but this bullet is advertised as being ideal for extreme velocity applications. For that reason I was surprised that the petals on the expanded nose were torn off. This also typically happens to X-Bullets at impact velocities in excess of 2700 fps. Since the bullet sans petals is square ended it will continue to make a generous wound at any velocity high enough to tear away the petals, so this is probably not a serious detriment.

The 140 gr Barnes X-Bullet performed in picture perfect fashion (I deliberately shot it at a lower velocity to prevent petal breakage). Although the undeformed shank of the bullet is as long as that of the J36 bullet (described hereafter) and longer than the HV bullet, it did not tumble. I do think the potential exists and I wish that all of these monolithic bullets permitted deformation farther back along the bullet axis. In a conventional lead cored bullet yawing may be a real detriment since a lateral impact with bone could cause the lead core to be ejected from the jacket, but with a monolithic bullet I am not sure that it is a problem. The possible danger is of being deflected off the intended shotline, but this may be a spurious concern. A tumbling X-Bullet proved very lethal on a warthog on our safari in Namibia.

The Lost River Ballistics J36 bullet is the successor to the J26 bonded core bullet of Warren Jensen. It is, like the GS Custom HV, turned from rod stock, in this case made of a copper-nickel alloy. It features a metal tip inserted into a socket in the bullet body and a generous boat-tail, combining (in the 7mm-140 gr bullet) for an advertised BC of .644! It was also envisioned for extremely high velocity applications where the high dynamic pressures created would enable its modest expanded diameter to create a large and very deep wound. The J36 yawed and tumbled at approximately the same depth as the HV bullet, also ending up base forward.

All of these monolithic bullets behave in some respects like the hard cast flat nosed handgun bullets and it is quite likely that the wet paper does not give a sufficient indicator of the actual damage that they inflict on tissue. On the other hand, I do not think it can be successfully argued that they create larger diameter wounds than softer lead alloy bullets, though they are comparable to the 160 gr Nosler Partition, long considered an excellent performer. What the monolithics do exceptionally well is penetrate, even through hard muscle and massive bone. They never seem to lose more than about 20 to 25 % of their mass and they create respectable wound diameters. The trend of future sporting weapons design to ever higher velocity seems to be favoring this technology, although a bonded core bullet with a solid shank, like a North Fork or a Speer Trophy Bonded Bear Claw, will not lose any more mass than a monolithic and will maintain a larger wound cavity during penetration.

Legend - (L-R) Premium bonded core .284 caliber bullets (unfired and recovered): (1, 2) 140 gr North Fork Technologies, (3, 4) 150 gr Swift Scirocco, (5, 6) 160 gr North Fork Technologies

I was most excited about the Swift Scirocco and I have to say that I am slightly disappointed, but only slightly. I had hoped for a bullet with the aerodynamic characteristics of a Nosler Ballistic Tip, but the massive wounding and deep penetrating attributes of an A-Frame, making a perfect all-purpose bullet. Although the Scirocco creates a generous wound diameter, its penetration is not exceptional, a bit more than is typical for most conventional bullets of this weight. That's not to say that it is poor; what I may have found is a worthy successor to my beloved Remington 154 gr ER-FB bullet.

In the same class is the new North Fork Technologies bullets, also featuring bonded lead cores and pure copper jackets. These bullets resemble A-Frames, Grand Slams or Bear Claws in shape and have modest ballistic coefficients. Unlike many custom bullets, they have been carefully designed and manufactured in order to expand well down to impact velocities of 1800 fps or less. Mike Brady tests each production lot in ballistic gelatin to verify the performance. This equates to roughly 100 yards greater effective range than for bullets which do not expand below 2000 to 2200 fps. The other noteworthy feature is the grooved base which is intended to reduce bore fouling. These bullets have jackets that are CNC machined rather than swaged so their accuracy is quite good (poor accuracy being a complaint levied against some other bonded core bullets). Weight retention in both was 100 % at the moderate impact velocities and the holes were very large for a 7 mm. At the high impact velocity of 3000+ fps, the penetration of the 160 grain bullet actually increased! This is relatively unusual behavior (compare with the Scirocco at low and high velocity for the more typical response). Observe how the character of the wound changed between ~2400 fps and ~3000 fps: the maximum cavitation increased in diameter and assumes a more ovoid shape, while the latter portion of the penetration tapers down more narrowly than in the lower velocity case owing to the more swept back aspect of the expanded nose. The North Fork is the best of the bonded bullets in my opinion. They are far superior to some designs with extremely thick hard bronze jackets that only look good in photos when used at high velocity, but that fail to open at lower velocity.

The Swift A-Frame produced very good performance, although its cavity was less generous than the North Fork moving 500 fps slower, and I mean no harsh cricism of this design. It is quite good. The only complaint is somewhat restrained expansion, especially at low velocity; however, it exceeds the worthy Nosler Partition and the monolithic designs in this regard, though they win out in penetration depth.

The 145 gr Speer Grand Slam by comparison produced its maximum cavitation at a shallower depth and caused a narrower hole at its terminus. It is also a good performer, just the same. It closely resembles the performance of the 160 gr North Fork impacting 300 fps faster.

Legend - (L-R) The old standbys (unfired and recovered): (1, 2) .284-160 gr Nosler Partition, (3, 4) .284-160 gr Combined Technologies Partition Gold, (5, 6) .284-175 gr Nosler Partition Semi-Spitzer (discontinued)

The Nosler Partitions in this case are clear standouts compared with their conventional counterparts, performing as expected. While producing slightly narrower holes than more conventional bullets, they penetrate significantly farther (about 17 to 25% more). Actually the 160 grain Partition creates a wound of equal diameter to the Speer boat-tail bullet as well as a 25% deeper wound. While some have critisized the Combined Technologies Partition Gold, I have to say that I like my one shot sample of its performance. It gave up nothing in penetration and produced a larger diameter cavity over its depth. My only concern is whether it will expand as well at the lower velocities as does the original Partition.

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5. Too Light for Big Game?

After my 2000 season experience using the .243 Winchester I don't feel terribly confident in this caliber for big game either. My brother killed a 140 lb doe and a 200+ lb buck with one shot each diagonally through both lungs using Winchester 100 grain Power Points. The doe sat down but didn't die for a full minute. The buck ran 85 yards. Neither bullet exited and the entrance holes couldn't be found until the animals were skinned. Both bullets seemed to perform reasonably well. He was hunting in alfalfa fields in Montana and neither animal escaped. I shot two does on separate days not long after that in Alabama and lost both of them as they ran into an overgrown clearcut full of shoulder high young pines and briar thickets. Neither left any discernible blood trail and I searched in a fan extending well over 100 yards through the maze of brush without finding the carcasses. The drizzling rain and countless other recent tracks didn't help. I was using the 100 grain Nosler Partition load shown in the Figure (compare it to the lightest 7 mm bullet). Obviously, the .243 calibers are "enough", but only just barely so. In open country this caliber is fine on lighter species of big game, but I won't choose it again for heavy cover. I suspect that the varmint loads illustrated would have proven instantly fatal. They might also have blown apart on the scapula or even a rib. It would be interesting to know the risk and probability tradeoff between the chance of a bullet failure and the likelihood of losing a mortally wounded deer. Regardless, I'll stick with my 7 mm.

The following data for standard service sidearm automatic and magnum revolver handgun ammunition further illustrates the relative (im)potency of the .22 centerfires as weapons for hunting big game. Recall also that heavy, large caliber, flat-nosed handgun bullets can be expected to penetrate 30 to 50 inches while creating a 3/4 to 1 inch diameter wound channel.

1 -- Martin P. Olsen, "9mm v. 10mm High Performance Ammunition Tests", Rec.Guns FAQ, IV. Comparative Firearm Information, G. Calibre Issues, http://www.recguns.com.

2 -- Independent testing by the author

The figure below depicts the wound tracks created in testing with saturated phonebooks by the .243 / 6 mm bullets described above alongside the wound tracks produced by a standard service sidearm (.40 S&W), a magnum revolver firing standard weight (170 and 210 grain) hollowpoint bullets (.41 Magnum), and a conventional softpoint from a .22 centerfire cartridge (.223 Remington). Clearly the .22 centerfire using this class of bullet is marginally suitable only for the smallest game animals. If premium grade bullets in .224 caliber perform as suggested by the data in the foregoing table, then the suitability of these cartridges for big game is less questionable, possibly comparable to the magnum handgun, but I have also read that the only reliable performance occurs (even using premium bullets) with impact velocities exceeding about 2900 to 3000 fps.

6. Large-Bore Bullets

Of some interest is the compared performance of some notably larger calibers, presumed to be proportionately more effective, particularly in terms of penetration (see Table and Figure).

Observe that the potent 45-70 yields very similar penetration as compared to the .308 caliber bullets examined in detail and generally less than the medium bore loads described in the preceding table. Necessarily these .458 caliber bullets typically produce wound tracks larger in diameter than produced by smallbore projectiles, but not evidently than medium bore bullets when the effect of generally higher velocities is considered (and compare the .458-300 grain Barnes X-Bullet at 1930 fps with the .284-150 grain Swift Scirocco described earlier).

Although most of these loads produce similar velocities, the two 403 gr Trophy Bonded bullets (an old design very similar to Barnes copper tubing bullets) exhibit the same penetration with different impact velocities, consistent with the observed behavior of .308 caliber bullets. This is further borne out by the 350 grain Hornady FN bullets in my testing at velocities 500 fps apart, where similar depths of penetration are found although the cavities produced are quite dissimilar. In contrast, when there is little or no expansion they penetrate roughly twice as deeply.

Jamison indicates in the reference that the 350 gr Hornady RN soft points yawed during penetration and were recovered in a base forward orientation. This curious result (from 2 shots) differs considerably from the behavior of the slower (1765 fps) and faster (3000 fps) tests. Probably the jacket failed to deform evenly; the photograph seems to demonstrate this failure. Nevertheless the penetration is the highest among tests of this bullet and the cavity produced must have been of respectable dimensions, so it is difficult to characterize the result as a failure. Surprisingly, the Barnes Original 300 gr failed to deform at a very high (for the 45-70) velocity of 1992 fps; only the exposed lead nose was scraped away. Deep penetration and probably a larger wound path was created by the similarly non-deforming Remington 405 gr soft point, but this had an impact velocity of only 1103 fps.

In my own testing two bullets were recovered in a sideways or base forward orientation: the 300 grain Barnes X-Bullet at both 1400 fps (sideways) and 1930 fps (reversed) and the low velocity Hornady 350 grain Interlock FN. The latter bullet is a new design very similar to the older round nose bullet, apparently in response to the demands of Marlin users who were concerned about the round nose impacting the primers in a tubular magazine. This bullet must be seated below the crimping groove to feed in a Ruger No. 1, which is not Hornady's fault, but Ruger's for making such a short throat, a long time problem on that rifle. The high velocity load created a gigantic cavity that exploded outward toward me (rather like the .338-275 Speer semi-spitzer had done at high impact velocity), but the bullet retained 93% of its weight! I am surprised that the X-Bullet lost its petals at the relatively low velocity of 1930 fps, but its cavity is gaping and so the walls are unusually thin. It could be improved by a narrower taper so that the petals opened but held on. It did not penetrate as I expected but it made a respectable hole. This bullet will expand at very low velocities as evidenced by the second shot at 1400 fps, which performed very similarly to a magnum handgun bullet.

The Speer 350 gr. FN is billed as a high velocity soft nose for the .458 magnum, so I did not expect much expansion at the 1930 fps impact velocity out of the .45-70, but it performed well. It also performed well at a near muzzle velocity (from the .458 Winchester Magnum) of 2400 fps, but at a very low impact velocity of approximately 1400 fps it apparently did not expand or did so only to a very slight degree and unfortunately exited the test box (Incidentally, this is the sort of hole that would be made by a non-deforming hardcast flatnose bullet, hence the need for a very broad flat point). It is a good bullet in the .45-70 where deeper penetration is required but needs a minimum velocity probably closer to 1600 to 1700 fps for expansion. I was impressed by the 500 grain Hornady RN softpoint at the rather modest velocity of 1985 fps. It cavitated a surprisingly large hole yet achieved just over 20 inches of straight-on penetration.

In the .450 Ackley Magnum the 400 grain Barnes X-Bullet performs about as well as the 500 grain Hornady soft point, and the 500 grain X-Bullet penetrates significantly deeper. Observe that the 600 gr Barnes Original bullet fired from a .460 Weatherby Magnum penetrates less deeply than the Hornady 500 gr softpoint, despite its greater sectional density; here being a classic example of the misleading character of the calculated sectional density of an unfired bullet as applied to its terminal effect. The extremely high velocities of the .460 Weatherby Magnum (though these impact velocities are practical muzzle velocities, not reasonable field conditions) removes bullets of normally robust construction from consideration as projectiles of choice to be used against heavy game at close range, though their use at extended ranges is perfectly acceptable. Again, magnum cartridges do not necessarily provide more killing power, merely extended range (and in this case a potential close range non-engagement zone for some loads).

1 -- Rick Jamison, "Big Power at Close Range", Shooting Times, May 1997.

2 -- John Wooters, "Premium Big-Bore, Big-Game Bullets", Guns & Ammo, December 1984, pp. 61,91.

3 -- Bob Hagel, ".460 Weatherby", Big Bore Rifles and Cartridges, Wolfe Publishing, Inc., 1991, pp. 328 - 332.

4 -- Independent testing by Øyvind Hannisdal

5 -- Brian Pearce, "The Underrated .444 Marlin", Handloader, Wolfe Publishing, Inc., No. 206, August-September, 2000, pp. 62 - 67.

6 -- Independent testing by the author

7 -- Kent M. Batchelor, "Penetration Test at the Linebaugh Seminar", http://www.sixgunner.com/linebaugh/penetration_test.htm.

8 -- Independent testing by Michael Strandberg

Legend - (L-R) Some tested .458 caliber bullet designs: (1, 2) 300 gr Barnes X-Bullet (unfired and recovered from 1930 fps), (3 - 5) 350 gr Hornady Interlock FN (unfired and recovered from 1400 and 1900 fps), (6, 7) 350 gr Speer Hot-Cor (unfired and recovered from 1930 fps)

Legend - (L-R) A range of .458 caliber bullets (recovered from wetpack tests): (1, 2) 300 gr Barnes X-Bullet (1400 fps and 1930 fps), (3, 4) 350 gr Hornady Interlock FN (1400 fps and 1900 fps), (5, 6) 350 gr Speer Hot-Cor (1930 fps and 2400 fps), (7) 500 gr Hornady Interlock RN (1985 fps)

V. Analytical Modeling of Terminal Ballistics