It’s obvious that lead is the main element in cast bullets and all are aware of the old adage “you can lead a horse to water but you can’t make them drink”. And surely you’ve led a group of folks at one time or another. But many of us inadvertently use lead when referring to the ramped transition from the chamber or free bore to the lands, for which leade is the more correct term. Many, many years ago when, as a novice shooter, I was reading and learning about chambers and bores, I remember this being a point of confusion.

SAAMI (Sporting Arms & Manufacturer’s Institute) defines leade as: “That section of the bore of a rifled gun barrel located immediately ahead of the chamber in which the rifling is conically removed to provide clearance for the seated bullet”. The key word here is “conically”, as in cone-shaped, otherwise completely removing the rifling results in free bore, defined by SAAMI as the: “A cylindrical length of bore in a firearm just forward of the chamber in which rifling is not present”. But SAAMI does recognize that lead and leade are used interchangeably by some.

When writing about chambers and bores it helps me to remember to use the correct spelling if I think of leade as an abbreviation or contraction of the leading edge of the lands.

Wayne

when the spelling "lead" is used the meaning is not confused as the meaning is determined by context

What if I tell you in writing that I am going to remove some of the lead from my barrel? If it was spelled leade, then everyone would know what I am talking about. I think that when we write anything down about guns or loads, that we should be as plainspoken as possible so as to remove any doubts as to the meaning of what we are saying.
I had not heard about spelling leade with the last e but I will use it now. Thanks Mac! Bob

Yep,
I always spell it "leade" and pronounce it with a long E like "LEED" as in BLEED.

The leade of a throat may be fully specified by stating the leade angle plus the diameter where it starts at the end of the chamber.

The throat is composed of the free-bore plus the leade.

The .416 Rigby has zero free-bore, the throat is purely leade, leade only.

My hand-drawn picture of the standard CIP throat for the .416 Rigby: There can be only one!
Outlined in red is the leade:

Since the leade of the .416 Rigby starts at a diameter that is .001" greater than the groove diameter of the barrel it does produce a "pseudo-free-bore" that is 0.067" long from end of chamber case mouth to start of any trace of rifling in the throat.

Then we could talk about "effective free-bore" depending on the ogive or nose shape of the bullet,
determining what length of jump of bullet from case mouth until rifling begins to be engaged ...

Effective free-bore can be longer than pseudo free-bore in a "zero-free-bore/leade-only throat."