Just curious about which lapping process you follow.
LBT and Beartooth both recommend the 50 stroke polish after lapping. IIRC, Beartooth recommends 320 grit Clover grease mix lapping compound & I'm not sure what LBT puts in his compound. Repackaged Clover? Looks the same. I have cans of 320 & 400 grit Clover at home.
To me, JB is a mild abrasive cleaner vs. a lapping compound.
I have used both, JB for initial cleaning of a new Handi barrel and Clover/LBT after firelapping microgroove Marlins, Rugers & Remingtons.