It has finely become clearer for me. I had some responses on another site (some of the people are on this forum as well) that also point out that it has nothing to do with the lock, but all to do with the trigger.
From One Fine Gentleman:
"The trigger that is in the rifle now mandates that the trigger is set (dropping that bar) so that it doesn't contact the sear arm of the lock,, that contact prevents the lock from going to full cock.
It's a target trigger only, it's meant to be used at a target range where a rifle isn't made to be ready to shoot until at the firing line or on the bench with the rifle pointed down range.
It would be un-safe to use that trigger set up for hunting."
And another:
"I agree, the single lever double set trigger is dangerous to use for hunting.
Because the trigger must first be set in order to cock the gun, any sharp impact to the guns stock could release the hammer/cock.
Even saying,
"Well! I'll just put the lock at half cock after I've set the rear trigger." isn't a safe thing to do.
When the rear set trigger is released it has a LOT of energy and it can bust the nose off of the sear or break the half cock notch catch off of the tumbler.
In either case, the hammer/cock will fall and can cause the gun to fire.
The only ways to safely carry the gun in the field is to leave the gun uncocked or, if it must be cocked, to have the nipple uncapped or the pan unprimed with the frizzen open.
That makes keeping an eye on the game while you put a percussion cap on the nipple or prime the pan and lower the frizzen a difficult thing to do.
Of course, the target shooters aren't bothered by this so they don't have the same problems."
So, I am going trigger searching! I want to find a trigger system that I have to do the least modification for.
Thank you,
Ron