I recently won this revolver on eGun.de and expect to receive it in my next shipment around four months from now. The serial number is K19XX, where the K prefix indicates revolvers with adjustable sights, originally fitted with a 4" barrel. According to Manurhin, adjusting the rear sight by a click (⅛ of a full turn) on the MR73 is equivalent to the following correction of the point of aim at 25 meters, according to the model and barrel length.
Sport model in .357 Magnum / .38 Special:
- 4" barrel, correction 7.7 mm
- 5¼" barrel, correction 6.3 mm
- 6" barrel, correction 5.7 mm
- 8" barrel, correction 4.4 mm
- 6" and 5¾" barrel, correction 5.2 mm
One variation that cannot be distinguished without removing the sideplate is the changeover from the “safety pin” music wire spring tensioning the hand in an early model of the MR73, to a flat spring that performs that function in the later models.
American-style handgun shooting reached Europe in the Sixties with Raymond Sasia, a judo instructor employed as a bodyguard by Charles de Gaulle, who was sent to study the shooting techniques of the FBI Academy in Quantico, Virginia. He returned to France with an FBI certification and founded CNT, a shooting school in Paris that taught range officers, French nationals at first, then foreigners. The latter, upon returning home, taught new range officers. Thus the method “Sasia” promulgated FBI’s revolver shooting techniques throughout the Western world.
One of the drills was the 7 meter fast response. It goes as follows: the gun is loaded with five .357 Magnum rounds and carried in a belt holster; in the pocket the shooter has 5 more loose .357 Magnum rounds. At the sound of a whistle, the range officers are given 25 seconds to fire the ten cartridges at the target located 7 meters away; the instructors have only 20 seconds. It turns out that in order to have the time to reload and fire the other five rounds in the allotted time, the first 5 rounds must be fired in less than 5 seconds to satisfy the requirements; no more than 3 to 4 seconds can be allowed for top placements.
At this rate of fire, in the original MR73 design that tensioned the hand with a “safety pin” spring, the hand did not have enough time to return to the ratchet and rotate the cylinder, and consequently it slipped over the ratchet, causing the firing pin to strike the primer of the last expended shell. Owing to the inertia of the hand thrown backward by Magnum recoil forces, the music wire spring was not strong enough to return it forward in time to engage the teeth of the ratchet of the ejector and ensure the rotation of the cylinder. Manurhin’s engineers were slow to understand why this happened to some police shooters, because the factory testers never managed to replicate the malfunction. Shooters training with S&W M10, M13, or M19 under similar conditions never experienced this malfunction. My 3" MR73 Defense & Police revolver numbered B1254 has the music wire spring. I never managed to replicate the malfunction, either.
Subsequently, the MR 73 design was modified with the new, stronger flat spring that required a shallow milled relief cut inside the sideplate, and was therefore not suitable for retrofitting without this difficult and costly modification.