My first "Rock-lock" was a Euroarm hawken...very frustrating, till I started using high quality english flints, thenit was OK, but not great. Sold it decades ago and had a custom gun built by a 'smith in Havre Montana. He used a Siler lock that he assembled and tuned himself. The fellow is an incredible flintlock shooter, I have seen him shoot a 50 yard offhand target with a 54 fullstock that scored 49-3X...the ten ring is 2" and X-ring is 1".
My full stock hawken flintlock will consistantly shoot out the ten ring at 50 yards and will keep five shots inside the nine ring at 100 off the crossed-sticks.The lock is so reliable it will fire upside down.
There are a lot of tricks to the shooting the rock-lock.
First...find a pin close to the diameter of the touch-hole, you do not want it tight not real loose ( I use a large paper clip)...prior to dropping your charge put the pin in the hole all the way through to the other side of the barrel, angle the pin to the back of the pan then close the frizzen, then load as normal.
I am getting ahead of myself here...before loading adjust your flint.
Use the pin as a gauge to adjust the flint in the jaws of the hammer. With the frizzen closed, and the hammer on half ####, adjust the flint in the jaws so the pin will pass evenly between the flint and frizzen, just touching the flint. Make sure the flint is sharp. The flint should contact the frizzen about two thirds of the way up the face of the frizzen. Make sure the frizzen spring is putting sufficient pressure on the firzzen as well...you should NOT be able to easily flip the frizzen open. If the flint does not contact the frizzen correctly, flip the flint over...it should be OK then. If you got as roller spring for thre frizzen get rid of it and put a good tempered leaf spring in.
When ready to fire, do not fill the pan completely full of FFFFG, put a teardrop shaped plile leading to the touch-hole...the narrow part next to the hole, the wide part at the outer limit of the pan...best to do this on the line.
Concentrate on your sights and trigger squeeze and you will be surprized.
Enjoy!!!!!
Cheers
Cheers