Re: Cold bore shot vs dirty bore shot
Although I don't remember the source, I KNOW I've seen credible testing that concluded beyond any doubt; it takes 4-9 shots to burn oil residue out of a bore. This before the bore could be considered stable in fouling. More interesting in it was that this also applied to NEW fouling from another powder type. In both cases, the tester was initially sure that reasonable efforts removed any offender to stable fouling.
My father taught me that a gun is to be put away cleaner than it was pulled. So I don't pull a gun unless I'm going to use it, & clean it either way.
To cover both concerns for barrels, I clean bores to bare metal, as verified with my borescope, after use -every time. That is, DRY bare metal. Then I prefoul with a dry burnish of WS2 and this is how the gun is stored(in a safe, in my house). All my bullets are also WS2 coated/waxed, and this is a condition of load development.
With this, my first shot is often my best.
That's where cold bore load development goes hand in hand with prefouling.