Mechanisms

Japanese matchlocks used two major types of locks, "Karakuri," so-called.
One has an outside spring, a sharp "V" bar spring located outside the lock plate.
The other has an inside lock which uses a coil spring inside the lock plate. Each type has a different system to release the lock, and there are six major styles. Most locks are made of brass and few are made from iron. The springs used are weak so the hammer hits the fire pan gently. It is essential that the ignition be fast for accurate shooting, so a finely-ground priming powder is used. A cover protects the priming pan; this cover is called a "Hibuta," and it is made of thick brass.

The barrels of Japanese matchlocks usually are seated very deeply in the gun stocks and are held securely by three or four bamboo pins. The barrels usually are finished with heated Japanese lacquer to produce a durable and attractive finish, and some barrels are decorated with precious metal inlays.

There are many varieties of matchlock sights and various combinations of front sights , called "Shosei" or "Mae-Meate," and rear sight , called "Shoumon," or "Ushiro-Meate," exist. Also the position of the rear sight is not always at the very rear of the barrel. Shooting was a kind of sport that even an old man could enjoy, so the rear sight often was located at the whimsical direction of the shooter, who was not necessarily a marksman. The blade of the front sights common to Western long arms is replaced on the Japanese matchlocks by a grooved one, so sighting requires aligning the two grooves of both front and rear sights with the target. There are many varieties of sights but grooved sights are common and it is clear that there were some rules for the marksmanship. A collector or shooter of original Japanese matchlocks today should not alter the sights because doing so lessens the value of these guns.

The trigger mechanism of the matchlock is a simple one. It does not need a strong spring and so the main spring is a weak brass one. Because of the matchlock's cheek stock the lock itself is long, and the bar that releases the lock is also long.
There are several shapes of triggers used with matchlocks, called "water drop," "oil drops," axe," "bell," and other descriptive names. Usually the trigger is separate from the lock and pivots in the stock on a bamboo pin.

About half of the Japanese matchlocks seen today do not have trigger guards.
The standard size matchlock is four feet and five inch long and has a caliber between 1/5 and 2 Monme (a unit of weight measure of the lead ball fired); the standard size matchlock has usually a trigger guard. Trigger guards are fixed by a pin which supports the guard plate.

The fire pan which holds the priming powder has a cover called a "Hibuta," and the barrel protector, a safety device also, is called "Ama-ooi." The Hibuta is made of thick brass and it covers the pan. It is opened by the right thumb just before firing, and it prevents fire from entering the pan, even if the burning match cord is located less than an inch above it. Opening the cover means a decision to fire has been made.
The Amaooi is a long brass plate located between the pan and the barrel. It protects the barrel from the ignition of the powder in priming pan.