Great point Steve!! I've played around with rotational inertia as it is effected by the center of mass and stability a bit. I have found that the farther aft the center of mass resides in a bullet the higher the rotational velocity has to be to keep it moving point forward and expand in what we consider a normal' fashion without exhibiting yaw and subsequently tumbling. Simple. Do you want the bullet to yaw and tumble? Maybe, maybe not.
The behavior of a bullet can be most easily thought of in terms of a gyroscope. As in gyroscopic stability, the faster you spin it the more likely it can resist an upsetting force and recover the rotational orientation and path that existed prior to the introduction of the upsetting force. Now this brings us to tumbling. Do you want the bullet to yaw and upset or hold it's orientation? Tumbling can leave a very substancial wounding track, don't get me wrong, however it is problematic in that it is seldom predictable in its upset track, fragmentation or in the depth that it initiates.
The farther aft the center of mass is the more likely a bullet will tumble and the sooner it will do it. Is it desirable or not? Maybe, it depends...
Next it brings us to the jacket, if there is one. If the jacket is heavy enough or hard enough to resist the forces acting on it the bullet will trade front to back and simply continue on in that orientation until it runs out of energy. This generally doesn't create a desirable hunting type wound. If the jacket is thin enough or soft enough to not be able to resist the forces acting on it, it will fragment or deform which can show dramatic wounding effects. Provided it happens quickly enough to shed into the vitals you are probably golden. If it is too delayed it will pass through the animal and make a large exit wound.
There is a lot at play that contributes to how, why and even if a bullet performs as we hope it will, we have seen this in the thread. Bravo Yorke, kudos to you for taking the time to put together this thread. I have enjoyed it and learned from it. Thank you.
The behavior of a bullet can be most easily thought of in terms of a gyroscope. As in gyroscopic stability, the faster you spin it the more likely it can resist an upsetting force and recover the rotational orientation and path that existed prior to the introduction of the upsetting force. Now this brings us to tumbling. Do you want the bullet to yaw and upset or hold it's orientation? Tumbling can leave a very substancial wounding track, don't get me wrong, however it is problematic in that it is seldom predictable in its upset track, fragmentation or in the depth that it initiates.
The farther aft the center of mass is the more likely a bullet will tumble and the sooner it will do it. Is it desirable or not? Maybe, it depends...
Next it brings us to the jacket, if there is one. If the jacket is heavy enough or hard enough to resist the forces acting on it the bullet will trade front to back and simply continue on in that orientation until it runs out of energy. This generally doesn't create a desirable hunting type wound. If the jacket is thin enough or soft enough to not be able to resist the forces acting on it, it will fragment or deform which can show dramatic wounding effects. Provided it happens quickly enough to shed into the vitals you are probably golden. If it is too delayed it will pass through the animal and make a large exit wound.
There is a lot at play that contributes to how, why and even if a bullet performs as we hope it will, we have seen this in the thread. Bravo Yorke, kudos to you for taking the time to put together this thread. I have enjoyed it and learned from it. Thank you.
