For your information: Quoted from the "Buffalo Arms Co." web site:
"Swiss and Schuetzen Sporting Black Powder has the following granule size:
1Fg .047"-.063"
1 1/2Fg .035"-.054"
2Fg .026"-.054"
3Fg .020"-.034"
Available in Swiss Powder Only 4Fg.... .009"-.020"
Available in Swiss Powder Only Null B.... .009"
Available in Schuetzen Powder Only Re-enactor... .009"-.063" "
Quote finished.
My take is that the Swiss 'Null-B' is Everything that will pass through a .009" screen, all the way to 'dust'.
The Schuttzen "Re-enactor" would have a very wide range of ignition and burn speeds due to its variable mix of screen size powder granules.
Best Regards,
Chev. William