OK, a few things.
First, I doubt five people in the world have ever measure the force it takes to cock a BB. So you're asking for data no one has ready to hand.
Second, sometime flints break from heavy contact with the frizzen but more often they are broken by the frizzen actually bouncing back on top of them after the cock falls. You can't see this with the naked eye, you can only catch it with fast motion film photography like has been done several times.
Thirdly, if you feel the mainspring is excessively hard, it can be re tempered.
I don't know of a good domestic BB lock. They basically all come from overseas factories and that can range from acceptable to awful. They're usually pretty junky locks, sadly, so if you want a slick, dependable arm you have a hobby on your hands.
Given all the reenactors all over the world who use BB's you'd think a good state of the art BB lock would have come out but the ones we have are good enough to go "ch-boom" half of the time which for most needs is frankly adequate.
Heck, I bet you could still sell muskets in Africa. Not everyone can afford a Kalashnikov.