I experimented with the frizzen spring pressure, and discovered that just a rubber band holding it shut was sufficient pressure, so I thinned the spring for the frizzen To about the same tension and it works remarkably well. This is on a Lyman deer hunter left-hand.I would think the frizzen spring would only need to be strong enough too hold the frizzen shut…keeping the prime in place.
The gun will fire even if the frizzen spring is missing or broken.
You just have too keep the lock in an upright position..
Not an ideal situation, but it can be made too work.
squint