Double lock
Sandydobie,
Welcome to the forum!
Sorry you didn't get an answer right away.
The double lock mechanism was an early double action design that was replaced with a single bolt around 1885ish on the smaller framed 32's and 38's. A definite improvement.
This double lock design remained on the large frame 44's throughout production for the top-break revolver.
It's difficult to say that it's safe to operate without an in hand inspection.
Generally speaking the first lock serves only to hold the cylinder in place until the action is worked using either single or doubleaction methods.
Also generally speaking it's not uncommon for this feature to be found worn after 100 plus years.
As long as the cylinder rotates and locks using both Single action and double action it is generally considered functional. Many many hundreds of thousands of bulldogs were actually designed to operate in this way during that same time frame. It was termed a floating cylinder that would lock up only by centrifugal force along with hand tension against the cylinder stops and they functioned perfectly as designed. Very fast shooters if functioning normally.
They were honestly designed to be shot double action. That was the concept of the DA Bulldog revolver and that theme remained with the large frame 44's.
Murph
