[PennSkeet]

... which presumes that with regard to reloading at intentionally low pressures (5K to 8K PSI) a fluffier low density flake type powder will be in general more accommodating of such low pressures (as regards maintaining consistent pressures and velocities at various extremes of temperatures) than would be the case for the various of denser ball type powders?

7K to 8K is NOT considered low pressure, especially in the 12 gauge. 6K and under would be considered low pressure. 7k to 9K is average pressure and 10K and above is considered by many to be high pressure.

 

[PennSkeet]

Too bad Trailboss is unobtainable for a while. It's the rare fluffy powder that ignites with little pressure.

Trail Boss is NOT a shotgun powder.

 

[PennSkeet]

If you said "it's not suitable for a progressive press", I would agree with you.
If you said "I don't personally use any loads not tested and published by a factory", that's another thing to say.

There's no such thing as a shotgun powder being suitable or not suitable for a progressive press.

I'm not really sure where that thought originated.

Hodgdon sells Trail Boss and they have no tested data available for shotgun use.

I don't really care if anyone outside of Hodgdon has tested Trail Boss.

Until Hodgdon produces shotgun data for their product, I will not consider it a shotgun powder.

You're quite welcome to view Trail Boss however you choose.