Michael Courtney
Member
.40 Caliber Pressure Wave Effects
We had an opportunity this weekend to perform an informal field necropsy on a 180 lb 7 pt buck shot with a 135 Grain .40 caliber Nosler JHP at approximately 1350 FPS impact velocity. Though fired from a muzzleloader, this impact velocity closely approximates the impact velocity of the same bullet fired from a .40 S&W. This load produces one of the larger pressure waves available from JHP ammo in 9mm, .40S&W, .45 ACP, or .357 Sig. This buck was shot during a special youth-only hunt, and the young hunter was gracious enough to allow a couple of scientists access to his deer.
The effects of the pressure wave on tissue were impressive. The bullet entered just in front of the third rib (counting from the back) on the left side, pulverized a large (1.5” diameter) on the inside of the rib cage and in the liver, entered the left lung producing a large (1” diameter) pulverized region, entered the right lung producing a pulverized region that gradually shrank in size to the recovered diameter of the bullet (0.58”), exited the rib cage just in front of the 11th rib (counting from the back) and was recovered in the muscles of the right shoulder. The direction of the wound agrees with the account of the shot that the buck was mostly broadside, but angled slightly away with his head down grazing.
According to the PCC-only view of handgun bullet wounding (espoused by Fackler/IWBA adherents), the expected wound channel (which assumes crushing is the only mechanism) should be roughly cylindrical in shape, and have a diameter roughly equal to the recovered diameter of the bullet. The volume of this expected wound channel is widely known as the permanent crush cavity (PCC) and given by the frontal area of the recovered bullet times the penetration depth (12”). This gives an expected wound volume of 3.17 cubic inches.
What we actually observed is a truncated cone region of pulverized tissue with a diameter of 1.5” on the entrance side, and gradually narrowing to 0.58” on the exit side of the rib cage. The actual volume of this truncated cone of pulverized tissue is 12.18 cubic inches, or nearly 4 times the volume predicted by the PCC-only view of wounding via handgun bullets.
In addition, we observed a region of severe to moderate hemorrhaging along the wound channel that was 5” in diameter at entrance, narrowed to roughly 3” in diameter at the medial surface of the left lung and gradually shrank in size to merge with the bullet diameter where the bullet exited the rib cage. This region of hemorrhaging has an approximately truncated cone shape with a volume of 119.3 cubic inches.
We believe that the pressure wave is responsible for this hemorrhaging, though we cannot rule out the temporary stretch cavity for some regions. However, the 5” diameter of hemorrhaging of the muscular tissue surrounding the entrance wound is much larger than the expected TSC at this point. This is the effect that hunters associate with high-velocity rifle bullet wounds and refer to as bloodshot meat. Since the pressure wave is more strongly directed backward than the TSC, it makes sense that this hemorrhaging is due to the pressure wave.
We also observed mild hemorrhaging along the abdominal walls and rear rib cage on the right side. This is the area directly opposite from the entrance wound, but considerably rearward from the point where the bullet exited the rib cage. Thus this region was out of reach of both the permanent crush cavity and the temporary stretch cavity, and it seems that the most likely cause of the hemorrhaging was the pressure wave.
Inspecting the site of the shooting revealed that the deer ran 54 yards (straight line distance) from where it was shot to the point where the carcass was recovered. This is in good agreement with our empirical models which predict the average drop distance from the IWBA-type PCC volume and the peak pressure wave magnitude. In spite of the absence of an exit wound, there was an extremely profuse blood trail spread along the path the deer ran.
The wounds we observed for the 135 grain Nosler JHP are very similar to those observed in earlier studies with the 115 grain Triton Quik-Shok at .357 Sig velocities. In both cases, there is substantial tissue damage and destruction beyond the tissue crushed directly by the projectile. These two loads generate comparable pressure waves.
The tissue damage we observed from the 135 grain Nosler JHP is markedly different from that which we have observed on earlier occasions with lower pressure wave bullets such as the 147 grain Winchester 9mm bullet at 9mm velocity levels. The tissue damage due to the 147 grain 9mm bullet is very much in accordance with the PCC-only view espoused by Fackler/IWBA adherents: a nearly cylindrical region of crushed tissue with a diameter well approximated by the expanded diameter of the bullet. There is little tissue damage beyond the tissue crushed directly by the bullet.
This same 135 grain Nosler JHP bullet is also available in 10mm. We estimate the pressure wave in the 10mm Double Tap loading to be 50% larger than the pressure wave generated at 40 S&W velocities. Interesting. The performance potential of this bullet is almost enough to make me trade in my .357 Sig.
Michael Courtney
We had an opportunity this weekend to perform an informal field necropsy on a 180 lb 7 pt buck shot with a 135 Grain .40 caliber Nosler JHP at approximately 1350 FPS impact velocity. Though fired from a muzzleloader, this impact velocity closely approximates the impact velocity of the same bullet fired from a .40 S&W. This load produces one of the larger pressure waves available from JHP ammo in 9mm, .40S&W, .45 ACP, or .357 Sig. This buck was shot during a special youth-only hunt, and the young hunter was gracious enough to allow a couple of scientists access to his deer.
The effects of the pressure wave on tissue were impressive. The bullet entered just in front of the third rib (counting from the back) on the left side, pulverized a large (1.5” diameter) on the inside of the rib cage and in the liver, entered the left lung producing a large (1” diameter) pulverized region, entered the right lung producing a pulverized region that gradually shrank in size to the recovered diameter of the bullet (0.58”), exited the rib cage just in front of the 11th rib (counting from the back) and was recovered in the muscles of the right shoulder. The direction of the wound agrees with the account of the shot that the buck was mostly broadside, but angled slightly away with his head down grazing.
According to the PCC-only view of handgun bullet wounding (espoused by Fackler/IWBA adherents), the expected wound channel (which assumes crushing is the only mechanism) should be roughly cylindrical in shape, and have a diameter roughly equal to the recovered diameter of the bullet. The volume of this expected wound channel is widely known as the permanent crush cavity (PCC) and given by the frontal area of the recovered bullet times the penetration depth (12”). This gives an expected wound volume of 3.17 cubic inches.
What we actually observed is a truncated cone region of pulverized tissue with a diameter of 1.5” on the entrance side, and gradually narrowing to 0.58” on the exit side of the rib cage. The actual volume of this truncated cone of pulverized tissue is 12.18 cubic inches, or nearly 4 times the volume predicted by the PCC-only view of wounding via handgun bullets.
In addition, we observed a region of severe to moderate hemorrhaging along the wound channel that was 5” in diameter at entrance, narrowed to roughly 3” in diameter at the medial surface of the left lung and gradually shrank in size to merge with the bullet diameter where the bullet exited the rib cage. This region of hemorrhaging has an approximately truncated cone shape with a volume of 119.3 cubic inches.
We believe that the pressure wave is responsible for this hemorrhaging, though we cannot rule out the temporary stretch cavity for some regions. However, the 5” diameter of hemorrhaging of the muscular tissue surrounding the entrance wound is much larger than the expected TSC at this point. This is the effect that hunters associate with high-velocity rifle bullet wounds and refer to as bloodshot meat. Since the pressure wave is more strongly directed backward than the TSC, it makes sense that this hemorrhaging is due to the pressure wave.
We also observed mild hemorrhaging along the abdominal walls and rear rib cage on the right side. This is the area directly opposite from the entrance wound, but considerably rearward from the point where the bullet exited the rib cage. Thus this region was out of reach of both the permanent crush cavity and the temporary stretch cavity, and it seems that the most likely cause of the hemorrhaging was the pressure wave.
Inspecting the site of the shooting revealed that the deer ran 54 yards (straight line distance) from where it was shot to the point where the carcass was recovered. This is in good agreement with our empirical models which predict the average drop distance from the IWBA-type PCC volume and the peak pressure wave magnitude. In spite of the absence of an exit wound, there was an extremely profuse blood trail spread along the path the deer ran.
The wounds we observed for the 135 grain Nosler JHP are very similar to those observed in earlier studies with the 115 grain Triton Quik-Shok at .357 Sig velocities. In both cases, there is substantial tissue damage and destruction beyond the tissue crushed directly by the projectile. These two loads generate comparable pressure waves.
The tissue damage we observed from the 135 grain Nosler JHP is markedly different from that which we have observed on earlier occasions with lower pressure wave bullets such as the 147 grain Winchester 9mm bullet at 9mm velocity levels. The tissue damage due to the 147 grain 9mm bullet is very much in accordance with the PCC-only view espoused by Fackler/IWBA adherents: a nearly cylindrical region of crushed tissue with a diameter well approximated by the expanded diameter of the bullet. There is little tissue damage beyond the tissue crushed directly by the bullet.
This same 135 grain Nosler JHP bullet is also available in 10mm. We estimate the pressure wave in the 10mm Double Tap loading to be 50% larger than the pressure wave generated at 40 S&W velocities. Interesting. The performance potential of this bullet is almost enough to make me trade in my .357 Sig.
Michael Courtney