These chambered the .410 MUSKET cartridge and were used for guard and prison duty.
The casing is a .303 which has not been tapered or necked. It is generally loaded with a small charge of chopped Cordite (like a shotgun powder) and a single .410" round ball with the case-mouth coned lightly over it to hold it in place. Shot rounds also were issued.
SOME were converted to handle the commercial .410 shotshell by deepening the chambers to 2-3/4 or 3". Length of the original round is 2.222". If only the chamber has been deepened, then the gun will have excess headspace, the .410 shotshell having a much thinner rim than the .063" of the .303. Loading your own on .303 brass, I find fun with a .375" BP pistol ball or two in a plastic .410 wad cup and a charge of Unique.
They are an historical anomaly: the last true MUSKETS made or issued for military use, a Musket being, by definition, a military shoulder weapon with a SMOOTH BORE.
Muskets are fun. Take it shooting and you'll find out.
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