If the jacket is thin, which means that the bullet expands easily, the effect is usually very good for clean lung shots. However, if the same bullet encounters a heavy bone before it has completely entered the lungs, the effect can be that it expands too rapidly and breaks up before it penetrates deeply enough to damage vital organs. Put simply, penetration is poor.
On the other hand, a bullet with a thick rigid jacket to ensure penetration, can perform less well in clean lung shots because the expansion is less dramatic. The result of this is often that the quarry runs longer after being hit. The deep penetration however, ensures that the animal’s vital organs are hit and the shot is fatal even if there is an impact on a heavy bone.
Velocity 1640 fps
Vulkan - Weight 180 gr Despite its low velocity, which corresponds to about 350 yds range from a .30-06, the Vulkan bullet expands.
Oryx - Weight 180 gr The Oryx has also expanded, but somewhat less than the Vulkan.
Swift A-frame - Weight 180 gr The heavy jacket of the Swift A-Frame has prevented the bullet from expanding significantly. However, penetration is very deep.
Velocity 2297 fps
Vulkan - Weight 180 gr At this velocity, corresponding to a range of 150 yds from a .30-06, the Vulkan bullet has really expanded. It is also clear, however, that this more notable expansion causes considerably less penetration.
Oryx - Weight 180 gr Notable expansion and good penetration due to the bonding which prevents breakup of the bullet.
Swift A-frame - Weight 180 gr Deep, wide, wound channel.
Velocity 2953 fps
Vulkan - Weight 180 gr Wide initial wound channel. However, penetration is quickly reduced because of the rapid expansion and increased diameter of the bullet, plus the fact that the jacket and the core have begun to separate.
Oryx - Weight 180 gr Wide initial wound channel but good penetration nevertheless. This is because the jacket and core did not separate, giving almost 100% weight retention.
Swift A-frame - Weight 180 gr Despite the very high entry velocity, the bullet has retained almost 100% of its weight. The small diameter of the mushroom allows deep penetration.