Side-lock refers to the type of construction, in which the individual components of the mechanism are mounted either side of a single plate.
A small priming charge over the touch hole is ignited with a lit piece of slow match or similar.
These hand cannons were ungainly: the difficulty being in holding and aiming the weapon while manipulating the slow burning fuse needed to fire it.
Slow match would be held clear of the flash pan in a spring-loaded pivoting arm (the serpentine).
Actuating the trigger or firing lever would release the serpentine, allowing it to rotate and dip the lit match into the priming pan.
Pyrite held against a rotating steel wheel produced a spark directed at the priming charge in the flash pan.
The mechanism would also remove a cover from the flash pan at the moment of firing, sliding it forward.
[12][2] The next advance in firearm design was the snaplock, which used flint striking steel to generate the spark.
The snaphance incorporates a mechanism to slide the pan cover forward at the moment of firing.
The doglock incorporates a second latch (or dog) as a safety mechanism that engages the cock in a halfway or half-cock position.
The flint strikes against the upright of the "L" and flips the frizzen forward to reveal the pan to the sparks created.
The miquelet lock also has a half-cock mechanism similar in function but differing in operation from the doglock.
The sear is a lever that pivots in the vertical plane perpendicular to the axis of rotation of the cock and acts much like a pawl engaging the catch points of a ratchet gear.
The half-cock catch-point is a V-notch into which the sear fits and cannot be levered away by the trigger to disengage the tumbler.
Initial patents are attributed to the Reverend Alexander John Forsyth, who use a fulminate powder delivered from a charger that was integral to the lock mechanism.
The action of cocking the hammer is used to rotate the cylinder and bring a loaded chamber in-line with the barrel preparatory to firing.
This is a significant departure from earlier lock mechanisms that were constructed about a single plate fixed to one side of a firearm.
The term lock is not generally used to refer to the firing or trigger mechanism of metallic cartridge firearms.
Side-by-side shotguns and hunting rifles continued to use side-locks until the advent of the boxlock patented by Anson and Deeley in 1875.
Side-lock shotguns have two separate lock plates mounted to the sides of the butt of the gun and not the receiver.