Wohlgemuth’s Break-Action Musket Conversion and Rifled Barrel Insert System

This unique breechloader began life as a Harpers Ferry Model 1842 percussion musket, a .69 caliber smoothbore muzzle-loader manufactured in 1855. Wohlgemuth completely overhauled the musket into a break-action breech-loading firearm. He fitted a hinged breech mechanism into the original stock and barrel, allowing the barrel to tip downward for loading, much like a shotgun. To secure the breech when closed, the original trigger guard was reversed and a cam-locking lever was added under the action. He also modified the nose of the percussion hammer to be better suited to strike the pins of the pinfire cartridges, and trimmed the wooden fore-end to accommodate the new hinge. Finally, an M1861 Springfield rifle-musket rear sight was installed on the barrel, giving the converted gun proper sighting for rifled fire. Each of these alterations was performed by Wohlgemuth himself, transforming the old muzzle-loader into a modern breech-loader while retaining its hefty .69″ bore, which closely matches the dimensions of a 12-gauge shotgun.

The Patented Rifled Barrel Insert (1869)

A key feature of Wohlgemuth’s system is the removable rifled barrel liner. In 1869, Friedrich Wohlgemuth patented this concept in the United States, Great Britain and France (U.S. Patent No. 90,214; British Patent No. 1945; and French Patent No. 86294). The invention is a half-length rifled barrel insert that can be quickly inserted into the musket’s smooth bore, effectively converting the gun from a shotgun to a rifle. The liner is about half the length of the modified 24″ barrel which is long enough for accuracy but short enough to carry conveniently. It slips into the 0.69″ smooth bore from the breech, and is machined with a small flanged breech at its rear. When the gun is closed and locked, this flange nests against the host barrel and is held firmly by the breech-lock, preventing the insert from moving. In use, the shooter could carry the extra rifled tube in a sling or pouch (like a bayonet) and install it on demand by breaking open the gun, inserting the rifled liner, and locking the action, the smoothbore musket becomes a rifle in seconds. Wohlgemuth advertised that the conversion offered “the facility with which a smooth-barrel gun can be converted into a rifle”. The long smooth barrel around the insert still provided a full sight radius for aiming, and the added weight near the breech improved stability when firing.

Trials and Demonstrations (1871–1872)

Wohlgemuth submitted his converted musket and its rifled insert to contemporary military trials. In June 1871, he entered one of his arms for evaluation by the New York State National Guard’s Small Arms Board. The Board’s records list “One Wohlgemuth, presented by F. Wohlgemuth, 89 Clinton Place, New York City” among the trial arms. At this stage, Wohlgemuth’s gun was a pinfire breech-loader on the Lefaucheux pattern (a break-open action typical of French pinfire shotguns). The Naval and Military Gazette reported that during the New York trials, the Board focused on more promising designs; ultimately, Wohlgemuth’s was not among those selected for state purchase (as Remington, Allin trapdoor, Peabody, etc. were chosen for further testing).

Undeterred, Wohlgemuth next submitted two muskets built on his system for the U.S. Army’s trials in 1872. These were evaluated by the Army Board convened to select a new breech-loading system with a report published in 1873 as Ordnance Memoranda No.15. Wohlgemuth’s entries were listed as trial guns No. 16 and No. 17. Both used his break-open mechanism; one of them was configured with the rifled liner installed while the other used the smoothbore barrel alone. The Board noted that the two arms were “essentially alike, and use pinfire cartridges. One of the barrels is provided with a rifled lining which, being removed,

shows a smooth-bore of larger caliber for…buck-shot”. This succinctly describes Wohlgemuth’s convertible shotgun/rifle concept in action. Unfortunately for Wohlgemuth, his rifles were withdrawn from testing before official accuracy and reliability trials were completed. By 1872–73, pinfire ignition was falling out of favor (the U.S. trials predominantly featured center-fire .50 caliber arms), so Wohlgemuth’s pinfire musket system was technically outdated despite its clever insert feature.

Later Developments and Patents

After these trials, Friedrich Wohlgemuth continued to refine his designs. He pivoted away from pinfire and adapted his conversion for rimfire and centerfire ammunition in subsequent versions. In 1869, he also patented an Improvement in Cartridges (U.S. Patent No. 96,373, issued Nov. 2, 1869), which introduced a reloadable metallic cartridge. This design consisted of a two-piece brass case composed of a front sleeve and a screw-in base. The primer could be replaced and the case recharged with powder and ball, allowing the shell to be reused many times. Wohlgemuth boasted that he fired 150 rounds from a single case in testing, and that a dud round could be easily fixed by unscrewing the base to replace the cap or remove the charge.

Wohlgemuth’s final known patent, U.S. Patent No. 162,512 (issued April 27, 1875), describes a cartridge loading device designed to charge cartridges with powder, wads, and shot. The apparatus includes a charging tube, adjustable ramming mechanism, and a set of guides and caps that ensure consistent sizing and packing of the components. This device reflects Wohlgemuth’s continued interest in ammunition technology, particularly in supporting the use and reloading of metallic cartridges that had become standard by the mid-1870s.

Friedrich Wohlgemuth’s break-action conversion and patented rifled liner system represent a fascinating interim technology of the late 1860s. By repurposing an outdated percussion musket, he created a flexible weapon that could serve as both a shotgun and a rifle. Technically sound and very accurate at long range, according to his claims, the concept nonetheless arrived as military small arms rapidly evolved toward purpose-built breechloaders. Wohlgemuth’s entry in the 1871–72 trials was ultimately a historical footnote. The surviving example of his converted Harpers Ferry musket, featuring a hinged breech and drop-in rifled barrel, offers a clear view into the inventive solutions explored during a transitional period in firearms development.

Sources and References

• U.S. Patent No. 90,214 (1869) – F. Wohlgemuth, Improvement in Breech-Loading Fire-Arms
• British Patent No. 1945 (1869) – F. Wohlgemuth, Changing a Breech-Loading Shot Gun into a Breech-Loading Rifle
• French Patent No. 86,294 (1869) – F. Wohlgemuth, Moyen de transformer un fusil de chasse ordinaire se chargeant par la culasse en une carabine se chargeant de même
• U.S. Army Board Report (1873) – Ordnance Mem. 15, Report of the Board of Officers on Breech-Loading Muskets
• New York State Trials (1871) – NY State Militia Board, June 1871 trials
• U.S. Patent No. 96,373 (1869) – F. Wohlgemuth, Improvement in Cartridges
• U.S. Patent No. 162,512 (1875) – F. Wohlgemuth, Cartridge Loading Device
• Consultation with Tim Prince (2025) – Expert assessment of U.S. military firearms; identified base gun as Model 1842 and clarified original vs. modified components.