Last year I went to shoot a new to me HC/PC flint musket and I forgot to clean it before taking it out to shoot. Previous owner had used oil which had of course accumulated at the breach. There was no way that I was going to get that black powder to go off. Removed the lock for good access to the vent hole. Put the rubber tip of the blow gun on my compressor to the vent hole squeezed the trigger of the blow gun and out it popped. Frequently it does not take a very high pressure setting on the air compressor to get it moving. Be sure it is pointed in a safe direction.
It won't be the last time that you will have to do this. But they get farther apart each time it happens. LOL
It won't be the last time that you will have to do this. But they get farther apart each time it happens. LOL