Gun question: Seat of a magazine or "c" of a magazine.?

You "seat" the magazine when you fully insert it to the stops, or the magazine locking mechanism engages. When you load an M16 you slap the base of the magazine upward to ensure it is seated, then pull the charging handle to load the first round.

The term could also be used to describe the seating of a bullet in a magazine or the seating of the cartridge in the chamber of the weapon.

I have been shooting guns for many many years and I have never heard such a term. I think the person is using an improper term. The closest I could come to guessing what the speaker had in mind would be that he/she was saying "seat" but there is no such term as "seat of a magazine". If that is what they were saying, I would guess that they were talking about the "base" of the magazine. The base of a magazine is the bottom if it. It is the only part that is visible when the magazine is fully inserted into the grip, or as the speaker called it "the handle". Referring to the grip as the handle is not incorrect but is very dated language. I just recently was reading a 1930s copy of an owner's manual for a .22 semi-auto handgun and it used the term "handle" instead of grip. So handle is okay just dated language.

I agree with the others

The ridgy portion would be the front of the serrated grip frame or front strap of an auto loader

I have heard grips of old revolvers referred to as handles in the old B westerns

The black plastic piece could only be the base plate/ floor plate on an auto loader

There are magazine spring seats but that is inside the magazine

It sounds to me that you are referring to the "base plate" or "base pad" of a autoloaders magazine.

The only parts of many handgun magazines that are either plastic or nylon is the "base plate" or the "follower". (And yes, before someone mentions that some magazine bodies are made of a plastic material over a metal tube (Glock, as an example) I am already aware of that).

The "ridgy portion" mentioned sounds like a autoloaders grip face that has vertical lines or checkering cut into it.

Therefore, the "black plastic piece" must be the magazine's base plate as the follower wouldn't be visible if it was already inserted into the firearm.

Is that what you meant?

I agree the bottom of the magazine is called the base plate. Maybe in England it is called something different?

Maybe a "FEED" ? There is no "C" or Seat