John Blisset revolver, found in Louisiana

[jimhallam]

The "generous chamber mouth" may well be because this type of transitional revolver sometimes has a gas-seal. When you cock the hammer, does the cylinder move forward slightly? The "Lang" type often has a cone on the rear of the barrel so the cylinder closes up the gap (the 7.62 x 25R Nagant revolver does something similar in that the bullet is completely inside the cartridge case, which is coned at the front and when the cylinder moves forward it is thrust into the bore and as the bullet moves forward it "gas seal" to give higher velocity." (I know that this is a cartridge gun but the cross-reference is to the PRINCIPLE involved)