How the Rhino works, part V: double
action lockwork.
Wednesday, November 10, 2010 Filed in:
Gunsmithing, Revolvers
As I mentioned last time, the Rhino's double action is a little
more conventional - but not a whole lot!
First, we need to take a look at the left side of the hammer. It
sits against the inside of the frame, and without seeing it you
won't be able to grasp what's happening.

The 'hammer sear' is
referred to by other makers as a 'double action strut'. In most
revolvers a sear protrusion on the trigger sits under this piece,
and when the trigger is pulled that protrusion lifts the strut
upward, which rotates the hammer back. At some point the trigger
extension slips out from under the strut, and the hammer falls.
When the trigger is released, the strut (which is spring loaded)
allows the trigger protrusion to slip back under the strut. The
Rhino’s hammer sear does serves the same task in the same
way.
(One thing about the Rhino’s hammer sear I found a little
concerning: every other revolver manufacturer makes this part
significantly larger and thicker, as well as orienting it to the
sear extension at a nearly vertical angle of incidence. In the
Rhino the part is smaller, thinner, and the force applied to it
puts significant upward strain on the part’s bend. Given the
generally good construction and material choice in the rest of the
gun I suspect it’s not going to be a problem, but it does
give one pause when considering what it’s asked to do!)
Anyhow, back to the action...

The operation on the Rhino
is similar to what I’ve described, except the extension isn't
on the trigger. Just as in single action, the trigger connects to
the interlink lever via the connecting rod and the interlink lever
is doing the actual work. Other than that, the operation is fairly
close to what we're used to.
(I've removed the mainspring and some of the Rhino's parts so that
you can see this a little more clearly.)

With the trigger partway
pulled, you can see that the hammer is being pushed back. In the
red circle (yeah, I know - it’s a poor excuse for a circle)
you can see the extension of the interlink lever reaching back
behind the hammer to engage the hammer sear. The hammer spring
lever, which is usually under tension from the mainspring, wants to
rotate counter-clockwise; a pin with a roller bearing rides in the
wide slot milled in the hammer (previous picture), which gives the
hammer it desire for forward movement. As the hammer is pushed back
by the interlink lever, it rotates the hammer spring lever
clockwise, against the mainspring tension.

The hammer is now back as
far as it is going in double action, and is about to slip off the
protrusion on the interlink lever.

The hammer starts to
fall.....

...and hits the firing pin,
igniting the round. The trigger is now ready to reset; where does
it get the spring power to do so? We'll look at that next time,
along with the hand - the two are linked together, and I can't talk
about one without going into detail about the other!
-=[
Grant ]=-