The .410" Lee-Enfield single-shot is not a Gun, not a Shotgun: being a military piece with a smooth bore, it is a MUSKET and that is what it is called: the Lee-Enfield MUSKET.
It is the LAST MUSKET ever built for military service.
The Rear Sight is pinned in a single position, the Body has a purpose-built Floor Plate Riveted into position, the Magazine is removed and the Magazine Well is blocked. Rifles built with Cutoffs will have had the Cutoffs removed. The Barrel is bored smooth and polished and the Chamber is reamed for the Cartridge, Small Arms, Ball, .410" Musket.
When Cordite-loaded .303 ammunition is being made, the Cartridge Casings are made straight first, finished, trimmed and primed. Then the Cordite propellant is loaded into the casing, as a bundle. Sixty strands of Rifle-specification Cordite makes a TIGHT package in the Casing; this becomes even TIGHTER when the loaded Cartridge then is Tapered and Necked prior to having the Bullet seated. This is why getting the Cordite out of a .303 round can be such a PITA: the stuff is skooshed in there VERY solidly.
But it was a simple matter to take straight, primed .303 cartridges from the loading line, load them with a bit of Pistol Cordite, a wad and a BALL. The result was a noisy short-range round with very limited penetration, quite suited to guarding barracks in urban areas. An added point was that, should the Musket be stolen (as so many .303s were), there was NO SOURCE OF AMMUNITION. A commercial .410 is too fat to fit the Musket chamber, the Musket cartridge's Rim is TOO THICK to allow a .410 shotgun to close. This suited the Army quite well because, unlike the Rifles, the Muskets were not stolen by insurgents. The Indian Prison Service recognised the value of the Musket in Riot control. If that 17 extra inches of cold steel on the muzzle does not deter people from doing silly things, you might have to shoot the ringleaders..... and you really do not want to put a .303 through the five guys standing behind the Target. The limited-penetration .410 Musket round and the arm in which it was used answered a lot of needs, so Muskets became popular in the Prisons.
Ammunition was made in single-ball and shot configurations by the Government ammunition factory. Hardly ANY of this ammunition has ever reached North America, although a handful of collectors are fortunate enough to have original specimens.
My own MUSKET was built at Enfield in 1914, went through both World Wars, ending up in India by some trick of fate where, utterly worn-out, it was transformed into a Musket at Ishapore in 1946. Original manufacturing data are found on the RIGHT side of the Butt Socket, conversion data on the LEFT side of the same part.
I make ammunition for my own Musket by first annealing and then opening out the mouths of fired, deprimed .303 empties. I open the neck and shoulder with a tapered punch until a .375" round ball will hold, use a toilet-paper wad and 10 grains of Unique, then fire-form. For a "service" load I use 8 grains of Unique, a commercial plastic .410 wad/shot-cup and TWO .360" (000 Buck) balls. At 80 yards, my Musket puts these generally right on the aiming-point and a couple of inches or less apart: GREAT for frangible targets but with enough WALLOP to knock down a Falling Plate. These efforts were discussed over coffee some years ago with a Czech friend who is a Consultant for the great CZ works at Brno as well as for Sellier & Bellot in Prague. About a year later, S&B introduced their popular multi-ball home-protection loads for the .410 SHOTGUN..... so the influence of the Musket will continue, even in places where people have never heard of the things.
So LOVE YOUR MUSKET. You are continuing a tradition which seems to have begun at Tannenberg Castle in 1399: the smooth-bored MILITARY shoulder weapon.
And yours is the VERY Last Musket.
Hope this helps.
I would love to have one.
