M1903 rifles made before February 1918 utilized receivers and bolts which were single heat-treated by a method that rendered some of them brittle and liable to fracture when fired, exposing the shooter to a risk of serious injury.
It proved impossible to determine, without destructive testing, which receivers and bolts were so affected and therefore potentially dangerous.
Can you or anyone else tell me, or steer me to a resource that can distinguish what the markings on the stock represent? Your trapdoor is the early narrow breech/square joint edition and the later ones have breechblocks which won't fit an earlier action. Al takes good pictures, gives excellent descriptions, and you can see what rifles, in various conditions, will actually sell for.
I'm unsure of the markings and what they represent, other than the serial number, which appears to date the firearm as either end of 1873 or early 1874 production. (2) The later blocks WILL, in the vast majority of cases, fit earlier receivers, but the profile below the hinge pin will not "match", and the block will overhang the receiver by about 1/32" each side.Later, armed with "trapdoors," Custer, though out-numbered, led his troops in an attack at the Little Big Horn against Natives armed with repeaters. This specimen attests to Army logic of that period, which thought repeaters to be wasteful of ammunition. The town was nearly destroyed during King Philip's War in 1675, but it was quickly rebuilt.As early as 1776, Continental Army colonel and future Secretary of War Henry Knox recommended the establishment of public laboratories, magazines, arsenals and foundries in secure locations for the production and repair of arms, ammunition, and other ordnance stores.The ammunition of the time was thought to be a contributing factor as well.The method of determining the proper heat treatment was less than scientific in that the men who were doing the heat treatment used the color of the steel to judge whether the correct temprature had been reached, When these rifles failed they shattered often causing injury to the shooter.