Randy,
About three years ago I got sucked into Mann's writings and labored through his book, to fully understand what he discussed and experimented with I struggled comprehending, until I did some of his experiments.  I followed some of his path's but with a little more recent equipment, (note that I said recent, not modern as that is relevant).

There is another piece of work published that discounts a lot of Mann's findings, it's called Rifle Accuracy Facts by Harold Vaughn.   I haven't made it through all of this book but there is a part of it that with present equipment and processes sheds light on potential culprits for the unexplained flyers you are inquiring about.  Bullet imbalance.   
In my spare time    I'm chasing some of this concept.  Mr. Vaughn was concerning himself with the unbalanced condition of jacketed bullets which I agree does exist but is there really enough to create an effect for any but the most regimented shooter?  But in the world of cast bullets? We study a cast bullet and with our two primary methods determine that it's good or bad - visual and weight, do we really know?   I have almost completed a static bullet balance fixture (caliber specific) and have a thought bouncing around my little pea brain for making a dynamic balancer (again caliber specific).

I tired of the lube sizer and have found that pan lubing and shooting as cast improved? or at least wasn't detrimental to my accuracy - so I eliminated one step in my reloading process.  If one of these methods I have going that can check balance of my bullets works - will I make that one of my steps in the future? Can't say...   I made a fixture once that when the bullet was sized, the base of the bullet was faced so it was square to the sized sides, wasted effort?  Probably.  Improvement to accuracy and consistency? maybe.  I still had an occasional flyer I couldn't explain,  average of 1 in 10?   

To answer an earlier question you asked, "has anyone recovered fired bullet?"  My work has been done with 45 and 38 caliber bullets with my "normal" loads both black and smokeless.  I don't know how well the oiled sawdust worked for others in these calibers but in my experiments my box was never big enough to capture them - another item I need to spend more time with.  The clay bank on the other side did stop things but generally with considerable distortion and base obliqueness was hard to measure.
Hopefully, someone else can chime in with their findings?
Regards, 
Greg

One might like to think that a cast bullet, carefully made, with the best equipment, would be a consistent item, bullet to bullet - however - as a cast metal, lead will crystalize in slightly different orientations internally, from bullet to bullet, depending on a variety of factors, over which we have little control. Small differences in how the bullet metal flows into the mould as it fills and cools may leave us with differing crystal orientations and slightly different strengths along different grain orientations, perhaps resulting in different flow under the pressure of the propellant gasses, and a slightly distorted bullet leaving the bore. Do I know this for a fact? Nope, but it's a possibility. Sometimes swaged bullets shoot better than cast, perhaps because the crystal structure is predistorted or normalized by the swaging process. Another mystery to ponder...

Air pockets that are cast into and traped inside of a bullet is also something to take into consideration. Actually all of the variables that can be taken into consideration are seemingly endless and swagging would be means to eliminate at least one.

Thank you for sharing Randy it's good information for one to think about and I appreciate the time and effort you set aside to share it.

cheatin_charlie
Seems to me that either a Leopold Oleo or a .063 thick low density polyethylene (LDPE) wad would flex when slammed by 20,000 PSI in a .45-90 or even a .32-40. Of course the Oleo wad would likely flex more than LDPE, or am I mistaken?

RSW wrote on Jun 14^th, 2019 at 12:18am:

The Oleo wad I believe is nothing more than what is now commonly called a grease cookie placed at the base of the bullet for lubrication coating the bore for not having to clean between shots.  The LDPE wad is used to protect the base of the bullet from black powder peening.  Now we are back to the original question of what causes the angular displacement of the bullet base?  Is it from powder peening or something in the bullet itself?  I know that a wad of LDPE or veg. fiber does improve the accuracy of black powder loaded ammo.

Lee Shaver has a thought on this.
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One shouldn't confuse opinions as have anything to do with wisdom if so Dan Theodore's opinions could make him seem to have more wisdom than maybe Lee. The later spent endless time and money out doing actual testing so was it actually knowledge and not wisdom that he really obtained.