I spent several years of my early married life as a Navy small arms maintainer during a period when the military Joint Services Small Arms Program was underway, resulting in the M16A2 designb modifications of the M16A1 rifle, the adoption of the M9 Beretta semiauto 9mm pistol and other deevelopments, not all of which were necessarily improvements, but at least increased the military knowledge database. I got *lent out* to several of the folks involved in the design engineering of several of the ongoing projects, including one for security forces shotguns, there being a wide variety of adapted commercial designs then in service due to the differing requirements of the various services and their needs. One of our first efforts was to summarize advantages and disadvantages of each design, several of which hadnt been manufactured for decades, and evaluate their characteristics for inclusion in a *unity* design. Safety, not surprisingly, was a big deal.
One requirement from the Navy: that the weapon not discharge with a chambered round when dropped from a height of 15 feet onto a steel plate, as when a weapon might drop from one deck of a ship to the next level down. Testing was commenced with a number of different types, muzzle down, horizontally, muzzle up, randomly positioned and under about every condition we could consider.
Conclusion: when so dropped horizontally, virtually ALL of the weapons we tested would fire, even with their trigger-blocking safeties in the safe position. Inertia would snap the hammer back far enough for the hammer to drive the firing pin forward and set off the cartridge. When dropped on the buttpad, the hammer would also snap back but either the pad would so cushion the impact that firing did not result or the hammer would engage the sear and simply remain in the cocked and safe position. The one gun which did NOT fire under those conditions was the Winchester M1897 shotgun, an external hammer design designed by John M. Browning in the Nineteenth Century.
There is one design that would fire as you pumped it- it is a police weapon, not legal to the general public- it fires as you pump it. Policemen/women would have access to such a weapon. What you describe would scare anyone- classic mishandling of a weapon and potentially deadly for you.
There are at least four commonly encountered commercial designs that would *slam fire* all are perfectly legal for civilian ownership in any jurisdiction in which the right to keep and bear arms is not infringed; they include the Winchester Model 1897, AKA the '97 Winchester, the Model 1912 Winchester, AKA the Model 12, the Stevens Model 520 and the those models of the Ithaca Model 37 without the later fitted trigger interrupter. The early Ithaca, without interrupter and fitted with an eight-shot magazine was a favorite of Navy SEAL Team point men operating in Vietnam, and was one of the shoitguns we tested that was most likely to fire when dropped horizontally. The SEALs didn't bother with the safety much, simply keeping their fingers off the trigger until ready to fire. Some *authorities* preferred working from an empty chamber, racking the slide when a round was needed. This was a less-than-ideal solution for those in the Army equipped with the Stevens Model 77E shotgun, which had only a four round magazine capacity.
Oh, the conclusions of our project: The Navy went to the Mossberg Model 500, later the product improved model. The Marines got the rebuilt Navy Remmie 870sa until the semiauto they wanted was developed [by Benelli] and the Army stuck with Winchesters.
Good info. Your testing reminded me of my formidable former mother-in-law who taught English to Hmong. Well trained in firearms, she had a habit of carrying a Browning Hi-Power (a Standard Hi-Power 9mm single action) in “cocked and locked”— chambered round, hammer back, safety on and full mag ready to autoload on firing. I about flipped when driving her daughter and her to dinner and adjusting the car seat, found the weapon under the seat, in a holster in that “condition”. What the Brits called “condition one”. She said no big deal, she did this routinely in Vietnam (was there in 52). Instant respect...and a reminder of the rule- ALL Firearms Are Loaded. I married her daughter.
I was thinking of the Ithaca as a “slam-fire” but Ive heard in some areas now one could get hassled about having one. Navy retirees told about the Ithaca.