bloorooster
The Old Hippie
While I agree that the rifling engagement swage marks create weak points that can start stress risers and premature failure at elevated rpm, 17 cal bullets have a much thicker jacket than .005"... more in the range of .020" to .050".
There is some variation between brands and types (varmint bullets usually have noticeably thinner jackets) but there is also quite a lot of variation in the size and length of the recess for the plastic tip, and the plastic tip itself.
When sectioning 17 cal 20gr bullets this was immediately apparent... what was also surprising was the presence of small voids in the plastic caused due to uneven cooling in the manufacturing process. When fired at 4,000fps (and spun at 320,000rpm) I'm sure these voids could easily be the cause of unexpected fliers or variable accuracy between batches of the same manufacturer's bullet.
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Yes sir, that is completely understood. I used those numbers for simplicity sake.
What you have posted is useful information and maybe a good example of how this thread should go. Thanks for that!
Hippie