Lefever bored their guns with a taper choke. On the taper choke there is no parallel at the muzzle, the choke being a taper for its entire length. Their full chokes normally run to around 4" in length with lesser chokes being shorter. I have often wondered if they didn't cut them all with the same reamer, the choke being determined by how far they ran the reamer. hus if a 4" long choke had a constriction of .032" then for .010" constriction the choke would be 1.25" long.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra