This is exciting! As to lube balls, etc, your BP lube sounds great.

For those who do not know, Vaseline works with BP fouling due to the fact it is actually a petroleum WAX, not an oil or grease, thus reacts differently than a Petroleum oil or grease would.

As to powder compression, try it both ways once you get a load for extended testing. We use slight compression in our ML's (RB or bullet) & ctg. guns to get even ignition and burning of the powder for lower shot to shot velocity spreads.