Joe, Don't worry about it.  It is an immutable law of nature.  It applies whether you believe it or not 

so now that the waters are muddied, let's go from gyroscopic stability to dynamic stability.
this is where nose shapes and airflow at certain velocities come into play, among other things.
it cannot be calculated and is yet not fully understood.
it can turn the best theory into doo doo.
and it becomes very important in the transonic zone.
it is possibly part of the reason why higher than theoretically optimum Sg (dynamic stability) is a better thing to aim for.
particularly in long range where vels go from high trans to possibly supersonic down to well and truly subsonic.
transonic is mach 1.2 down to mach 0.8.
just crossing the sound barrier is irrelevent.
keep safe,
bruce.
keep safe,
bruce.

Joe:

Here is the explanation of Don Millers formula to caculate the gyroscopic spin factor:

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And here is a link to an Excel spreadsheet that makes it much easier to use the formula by just adding the input variables into the spreadsheet:

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- first download yourself a copy; enable editing at the top, so you can enter new variables

- as you change the velocities or barrel twist or bullet length plus its weight the Sg will be recalculated for your caliber

- and you can also determine if it will still be OK under changing weather conditions.