Swivel Guns or Patarero
Swivel guns or Patarero were small guns that were mounted along the railing of a ship. Their mount allowed the gun to swivel in a full circle to allow reloading as well as an easier way to traverse the gun quickly.
Compared to most cannons, swivel guns were small. While the size varies many samples seem to have barrels between four and seven feet firing with a bore between one or two inches.
The purpose of the swivel gun was to allow the sailors to repel boarders so they normally did not fire a solid shot but were loaded with grape shot or small pellets. Sometimes even stones or scrap iron were fired from the guns. The mounting on the rail gave a steady platform to insure accurate fire as well the ability to fire large caliber rifles or small cannons with little or no recoil to the operator.
The guns would usually be loaded just before an engagement but not mounted until the enemy began to close. It was then a simple matter to lift the light weight cannon (fifty to one hundred pounds perhaps) into its socket mount and let go with a mini broadside just as the enemy boarded. By not mounting the swivel guns until the last second, the enemy would be at a loss for where the weakest place to board might be. Also a ship would not need as many swivel guns if they remained unmounted because they could be moved to where they were needed. That is, if the enemy were preparing to board on port side all the guns would be mounted on the port side because there would be no need for them on the starboard side.
Swivel guns were relatively small and were not effective at extremely long range, but at close range against a men armed with pistols and swords, they were devastating. One interesting feature of many swivel guns was that they were breach loders.
Breach Loaded Swivel Gun
The breach block rest in a trough at the back of the gun. To load the gun, the block is lifted out of place, the round (in this case a bag of musket balls) is pushed forward in the the barrel. the gun powder is shoved in next. and then the solid breach block is dropped in place and pushed forward, securing the powder and locking the breach. A pin is used to prick the powder bag and then more powder is added to the touch hole. The gun is ready to fire.
After firing, the breach is removed, the barrel is swabbed, and the process is repeated.
The long pole is attached to the bag of the gun to aid in moving and aiming the gun.