1. If the powder experiences abrasive friction, it will wear down. The only questions with a well defined experiment would be time and abrasion rate. How much time ? How much empty case space ?
No it won't. ANY type of powder is tough stuff. It resembles a plastic, it's hard and dense. It also just happens to have a lubricant applied to it, graphite.
The graphite is there to prevent clumping, also to aid in flowing through a measure.
Nobody is going to introduce an abrasive into a powder charge. It would NOT
be good for the barrels. Load density is another factor, less than 90% would allow plenty of movement. Now, a friction reducing lubricant, on a tough powder particle with limited movement, is a no-brainer, no change to the structure.
Next claim to be made is the movement of the powder against itself will remove the flame retardant that coats each granule to control burn rate. Oh?¿ Just where is it going to go? It was applied by means of tumbling the powder and flame retardant in a vessel! Trapped inside the cartridge case, it gets reapplied if it in fact is knocked loose.
The primer compound is constrained by the primer cup, is constrained by the case, and the constraining material has very different physical properties from the material it constrains.
It's pretty obvious you don't understand how a primer is constructed. The "primer compound" is inserted as a wet paste into the bottom of the brass cup. It has a paper disk on top of it to allow the wet pellet to adhere to the cup, not the punch. It dries as a solid disc, it's not a powder
! There will be NO
change to the primer from tumbling.
As for the tip of a bullet striking a primer to fire it, there just isn't enough motion to provide the force necessary to do it. Consider the amount of force present on the tip of a firing pin, where in a tumbler is that much force present?