I would try for a thicker lube but. I have this nice all brass "cake decorator" grease gun I got from Dixie Gun Works. I can just squirt it in without a big mess, level it with my thumb. When it gets a little cold on the range, I can just about squeeze it out. Besides, will the thicker lube withstand the blast any better?
Black powder shooting is just a big mess and hassle anyway!! Aint it great??
Gascheck