First, we should go into the origin of the name: This repeater was actually invented by an unknown inventor in the 17th century, but many of them were later manufactured by the Kalthoff family of gunsmiths and hence, they are now commonly referred to as Kalthoff repeaters.
The first known member of this gunsmithing family was Herman Kolthoff (1540-1610), who came from the town of Kultenhof in the Westphalia region of Germany (back in Herman Kolthoff's times, this area was part of the Danish duchy of Schleswig). He was a well known and rich person, famous for his iron manufacturing factories. He had several sons, who served as gunsmiths for various royal families across Europe: Peter Kalthoff (1600-1672), who served Fredrick III of Denmark as Head of Armory; Matthias Kalthoff, another Danish gunmaker; Caspar Kalthoff the Elder (1606-1664), who served under Charles I in England; Henric Kalthoff (1610-1661) who founded several ironworking foundries in Sweden and Norway etc. Some of their other descendants were also gunsmiths, e.g. Caspar Kalthoff the Younger, son of Caspar Kalthoff the Elder, who served as gunsmith for both Charles II of England and Tsar Alexis I of Russia.
The Kalthoff repeater is a smoothbore musket with two magazines. The first magazine is located in the forearm section of the musket and contains round bullet balls. A second magazine is located within the stock of the firearm and stores gunpowder.
A Kalthoff repeater. Click on image to enlarge.
Much like the lever-action rifle which was invented two centuries later, the trigger guard is actually a lever that helps operate this weapon. Upon pushing and pulling the trigger guard, the mechanism puts a charge of gunpowder and a ball into the breech of the weapon and then cocks the weapon. A small carrier device carries the powder from the magazine to the breech, to prevent the danger of the flame reaching the powder magazine. The user only has to manipulate the trigger guard lever, add some priming powder to the firing pan and the weapon is ready to fire. In some models, there is no need for the user to add priming powder to the pan manually, as there is a third magazine to feed the priming powder automatically.
Firing mechanism on some early models were wheel-locks and later models were flintlocks. Early models held six or seven shots, later there were some twelve shot models made and even one that claims to hold thirty shots. Typical reload time was one or two seconds, which gave this weapon a huge advantage over any other weapon in the 17th century. In fact, it wasn't until the middle of the 19th century that any other weapon came close to matching the rate of fire of a Kalthoff repeater.
However, this type of weapon was mostly used by rich people only. The mechanism was complicated and needed a specialized gunsmith to assemble and repair it. Also, wet powder and powder fouling could jam the mechanism easily. Therefore, this made it unsuitable for general military use and only rich people and elite military units used it. One example of military use was about 100 of these guns used by the Danish Royal Foot Guards in the Scanian war.
Some fine examples of this type of weapon exist in museums today:
Seven shot Kalthoff repeater
The above fine hunting gun is a seven-shot model that was made in London in 1658 and is now in the Moscow Kremlin museum. Inscriptions on it say that it was made by Caspar Kalthoff the Elder and Harman Barne (otherwise known as Haerman Barnevelt). This weapon was presented to Tsar Fyodor Alexeevich of Russia in 1664, by the British ambassador Prince Charles Howard. A similar gun with the inscription, C. Kalthoff, from around 1660, is in the Royal collection in Windsor Castle.
The gun has a seven bullet magazine in the fore-end and a powder magazine in the lock part of the wooden stock. In the safety catch is a transporter that holds a little more gunpowder than is necessary for firing. To reload, the user points the gun upwards and then moves the trigger guard 180 degrees forward and back. This has the effect of moving the sliding blocks to load a bullet and gunpowder into the breech and cocks the weapon. The remaining gun powder that is left in the transporter is then tipped out on to the priming pan and the gun is ready to fire.
The gun is made of steel, copper alloy and high quality walnut wood. A hunting scene featuring dogs and a deer are engraved on the lock plate, a dragon is engraved on the cocking piece and there are other decorative engravings, carvings and gold inlays on the weapon as well.
The Kalthoff family were not the only people that made this type of firearm though:
Five shot repeater
The above example can also be found in the Moscow Kremlin museum. It is a five-shot repeater and was made in London around 1660, by the above mentioned Harman Barne (Haerman Barnevelt). Harman Barne was a Dutch gunmaker, who moved to London and became a Gunmaker to King Charles I and Charles II, as well as Prince Rupert of England. This fine weapon is also made of steel and walnut wood with fine engravings, carvings and gold inlays. Unlike the previous example, this weapon has a rifled barrel with 8 grooves in it.