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The Kalthoff repeater was a type of repeating firearm that appeared in the seventeenth century and remained unmatched in its fire rate until the mid-nineteenth century. As its inventor is unknown, it is named after the Kalthoff gunsmiths who came to be associated with the design.
The Kalthoff had two magazines, one for powder and one for balls (some had a third for priming powder). A single forward-and-back motion on the trigger guard powered a mechanism that deposited a ball and load of powder in the breech and cocked the gun. Within one or two seconds, it was ready to fire again. A small carrier took the powder from the magazine to the breech, so there was no risk of an accidental ignition in the reserve. Early Kalthoff guns were wheellocks, but later they became flintlocks. Some carried six shots, but one claims in an inscription on its barrel to have thirty.
Despite having a remarkably fast fire rate for the time, the Kalthoff could never have become a standard military firearm because of its cost. The mechanism had to be assembled with skill and care, and took far more time to assemble than an ordinary muzzle-loader. Also, all the parts were interdependent; if a gear broke or jammed, the whole gun was unusable and only a specialist gunsmith could repair it. It needed special care; powder fouling, or even powder that was slightly wet, could clog it. Since it was so expensive to buy and maintain, only wealthy individuals and elite soldiers could afford it.
The Royal Foot Guards of Denmark were issued with about a hundred of these guns, and they are thought to have been used in the Siege of Copenhagen (1658-59) and the Scanian War. Others were ordered for private use or for demonstration.