Tagan P10

The P10 pistol originated around the turn of the 20th century as the result of a search for a suitable self-loading (or semi-automatic) pistol to replace the variety of revolvers then in service. Fanaglia was adopting new firearms at a phenomenal rate. The next decade would see a similar pace, including the adoption of several more revolvers and an intensive search for a self-loading pistol that would culminate in official adoption of the P10 after the turn of the decade.

Hiram S. Maxim had designed a self-loading rifle in the 1880s, but was preoccupied with machine guns. Nevertheless, the application of his principle of using bullet energy to reload led to several self-loading pistols in 1898. The designs caught the attention of various militaries, each of which began programs to find a suitable one for their forces. In Fanaglia, such a program would lead to a formal test after the turn of the 19th to the 20th century.

During the end of 1902 and start of 1903, a test of self-loading pistols was conducted, which included entries from Tagan Arms (the M98 "Box Cannon") and 7 Companies, Inc. (the Lischer-85).

This led to a purchase of 1,000 7C Lischer pistols, chambered in 7.65x21mm Parabellum, a bottlenecked cartridge. During field trials these ran into some problems, especially with stopping power. Other governments had made similar complaints. Consequently, 7C produced an enlarged version of the round, the 9 mm Parabellum, a necked-up version of the 7.65 mm round. Fifty of these were tested as well by the Fanaglian Army in 1903.

Fanaglian units fighting Yat'siminoli guerrillas during the First Oulish War using the then-standard M98 pistol, in 7.63x25mm Tagan, found it to be unsuitable for the rigors of forest warfare, particularly in terms of stopping power, as the Yat-siminoli had very high battle morale and frequently used drugs to inhibit the sensation of pain. The Fanaglian Army briefly reverted to using the Tagan Thunderhorse .45 in .45 Long Colt caliber, which had been standard during the late 19th century; the heavier bullet was found to be more effective against charging tribesmen, but the slower reload speed proved a hazard in the unpredictable Yat-siminoli forests. The problems prompted the then–Chief of Ordnance, General Joseph LaPierre, to authorize further testing for a new service pistol.

Following the 1904 Chirac-Tagan pistol round effectiveness tests, Colonel Phillipe Chirac stated that the new pistol "should not be of less than .45 caliber" and would preferably be semi-automatic in operation. This led to the 1906 trials of pistols from four firearms manufacturing companies (namely, Tagan Arms, 7 Companies, Inc., Nguyen Weapons Systems Incorporated, Vitzburgian Royal Arms Manufacturer, and Black Shield).

Of the four designs submitted, two were eliminated early on, leaving only the Tagan and 7C designs chambered in the new .45 TAP (Automatic Tagan Pistol) cartridge, which was essentially a rimless, smokeless-powder version of the older .45 Long Colt. These two still had issues that needed correction; a series of field tests from 1905 to 1910 were held to decide between the 7C and Tagan designs. Both designs were improved between each testing over their initial entries, leading up to the final test before adoption.

Among the areas of success for the Tagan was a test in the spring of 1910 attended by its co-designer, Martin Tagan, who had taken over the P10's development after the death of his father. Six thousand rounds were fired from a single pistol over the course of two days. When the gun began to grow hot, it was simply immersed in water to cool it. The Tagan gun passed with no reported malfunctions, while the 7C design had 37.