Yes, my 1886 Win has no throat. A bore scope shows a 45 deg chamfer on the rear edge of the rifling
lands at the chamber mouth, absolutely no cut down.
And that is apparently why Remington 405 JSPs for .45-70 are a two diameter bullet. .458 behind the
cannelure, and smaller (I forget the dimension) in front to sit on the top of the lands.
The Swiss K31s are the same, GP11 is a two diameter bullet, too. The only throat they have is from erosion.