Curator
Member
The Martini Henry has several "carry-over" detriments just like the Springfield trapdoor. The M/H was designed around a cartridge (577-450) that was chosen because the Brits had the machinery already partly set up. The 577-450 is the .577 Snider slightly lengthened and necked down to .45 caliber. The first cartridges were coiled brass foil around a steel base plug which gave problems with extraction when the gun became fouled. A drawn brass shell helped with this problem, so did modifying the extractor and mounting a longer lever. The 577-450 cartridge was loaded with 85 grains of high quality powder that did not produce a lot of fouling. Nonetheless, the "Henry-rifled" bore had a peculiar 7-sided geometry and a looooong tapered throat to deal with fouled throats. The recoil of the standard load with the 485 grain bullet is "quite stout" and I wonder how the 5 foot 5 inch 145 pound Tommie Atkins stood up to it and could still shoot accurately.
The bottle-neck design proved to foul more than a straight tapered cartridge when loaded with black powder. The Brits added a cup-shaped bee's wax wad under the bullet to help keep the fouling soft and paper patched the .450" diameter bullet to help prevent bore leading in the .468 groove bore. The Henry rifling did a pretty good job of swaging the round bullet 7-sided with sharp lands in the "corners" of the heptigon, and sealing off the powder gas once the bullet got into the bore proper. All of this special engineering to salvage and use an obsolete cartridge design! In 1882 the Brits redesigned the cartridge and introduced the .402 Martini Henry which was straight-tapered but used the same head diameter, pathetically thin rim and 85 grains of powder. A longer operating lever was added to assist in extraction at the same time. (MkIV) The bullet weight was reduced to "only" 400 grains so it probably kicked a bit less. Luck for them the .303 round was adopted so few if any were actually issued to their troops.
The bottle-neck design proved to foul more than a straight tapered cartridge when loaded with black powder. The Brits added a cup-shaped bee's wax wad under the bullet to help keep the fouling soft and paper patched the .450" diameter bullet to help prevent bore leading in the .468 groove bore. The Henry rifling did a pretty good job of swaging the round bullet 7-sided with sharp lands in the "corners" of the heptigon, and sealing off the powder gas once the bullet got into the bore proper. All of this special engineering to salvage and use an obsolete cartridge design! In 1882 the Brits redesigned the cartridge and introduced the .402 Martini Henry which was straight-tapered but used the same head diameter, pathetically thin rim and 85 grains of powder. A longer operating lever was added to assist in extraction at the same time. (MkIV) The bullet weight was reduced to "only" 400 grains so it probably kicked a bit less. Luck for them the .303 round was adopted so few if any were actually issued to their troops.