Lefever claimed in a 1909 Forest & Stream ad to have originated "the taper system of choke boring".
This is the description in Hunter-Trader-Trapper August 1912
Click here, then on p. 73 for the entire article
http://books.google.com/books?id=Uy...=onepage&q=Lefever%20gun&f=false

[Linked Image from photos.smugmug.com]

An occasional Lefever 12 gauge has bores tapering from the breech to the muzzle (.756 to .708 and .715 courtesy of Daryl Hallquist), some have a parallel bore and choke taper of 4 inches, and others a standard 2 – 2 1/2 inch taper.