Pyro and 777 are not very good as pan powder, they are propellant rather than explosive and need to be in a confined space to burn properly.
That said they should still work though no where near as reliably.
There are talks underway to allow shooters to have a small amount of BP (perhaps 2.5k) without an explosives license. Many of us participated in the consultation.
“If a cricketer, for instance, suddenly decided to go into a school and batter a lot of people to death with a cricket bat, which he could do very easily, I mean, are you going to ban cricket bats?” :- Prince Philip said after Dunblane