"Our System of Multiplied Choke Boring Gives Better Pattern and Penetration Than Any Other System of Boring" and "No Extra Charge for our Multiplied Choke Boring. It Produces better results than any other method, No other manufacturer can use our system of Choke Boring."
I can't however find any documentation in period sporting magazines or books as to what "multiplied choke boring" was.
Several U.S. makers, including A.J. Aubrey, Lefever, and esp. A.H. Fox used the phrase "taper choke bored" to contrast with swaged or jug chokes. 12g Smith guns typically had a 1 1/2" taper section to an about 1" parallel section at the muzzle; some LRWF tapers were longer, and Fox 12g guns have an about 4" choke taper.
Daryl Hallquist has confirmed that an occasional Lefever 12 gauge has bores tapering from the breech to the muzzle (.756 to .708 left and .715 right on one gun) but I am unaware of any Smith gun so bored.