As already mentioned...I'd go to FFF in real black powder like Goex...Pyrodex was developed in the 70s so it could be transported by UPS...It requires a hotter ignition...

Another thing you might try...I replaced the drum on a CVA for a friend a few years back...the original drum didn't have a taper or cone where it screws into the barrel...I put one on his with a coning tool...this allows the powder to flow into the drum easier...You must have powder under the nopple for a percussion to ignite quickly...Good Luck...