Sometimes reversing the fint works, ie: bevel up to get a lower strike, or bevel down to get a higher strike, but watch where the sparks fall in any positon. You want them in the pan, not everywhere but in the pan. Adjusting in and out also effects spark fall, elevation of the strike and intensity of the sparks. Different sizes work best in different locks. The size listed for your lock, might not be the best size or shape - something you must learn for each flint lock you have. They can be particualar.