H.B.C. Pollard in his book,History of Firearms , published in 1926, page 104,describes a gun in his collection as follows:
"A hammerless flintlock sporting gun made in Prague, Bohemia, by Stanislaus Paczelt, in 1730- A steel thimble has been brazed into the muzzle as an internal liner to the barrel. This is the first known specimen of a choke or restriction at the muzzle designed to concentrate the pattern of shot."

Roy Hebbes