Larry Gibson
posted this
21 February 2019
Appears to he a very generous chamber with a very large neck portion of the chamber, possibly a milsurp 7x57?
All of those terms are inclusive in the term "throat" and are, often, meant to be the same thing. However, they are not really the same thing.
The throat in the picture begins ahead of the case where the pound cast rounds off and then is straight to the beginning of the rifling.
The mouth of the throat is that part that rounds off ahead of the case and looks a bit like a shoulder. The mouth is considerably more pronounced in your chamber probably because it is a milsurp chamber?
The freebore or ball seat is that straight (may have a slight taper to it if it is long) portion from the mouth to the beginning of the rifling.
The leade is from where the rifling begins tapering forward to bore diameter or where the taper stops.
That is basically the distinction between those terms. However, you will see them used incorrectly and interchangeably in respected publications and by respected writers. Unfortunately there doesn't seem to be a "Webster's Dictionary" of ballistic terminology. Even in dictionarys we find the terms used interchangeably and even incorrectly.
For a proper "fit" of your PP'd bullet to the throat it should be of diameter sufficient to slide tightly into the freebore part of the throat to the leade without damaging the PP. In recent times, on an other forum, we find "fitment" to be a term used to describe the correct fit of a bullet to the throat. But that term is also incorrect as it is define properly as "1. fittings 2. equipment 3. furniture. Many have their own idea of what the terms mean.
The problem with different ideas of what the terms are and not using the correct (same if you will) terminology is confusing when, especially when giving advise. We, the reloading fraternity, demad precise information regarding loads, powders, charges, bullet weights, diameters, etc. yet we can't seem to use the correct terminology on things such as this. Strange eh?
LMG
Concealment is not cover.........