Hi.
Yes that is perfectly normal, indeed I would be more surprised if their had been a crystal (display) back

Some pocket watches have a metal cover (cuvee) between the outside back cover and movement, but that is normally with pocket watches with a key wind to protect the movement as you wind it.
I suspect yours winds and probably sets from the crown

Regards

 

I keep seeing the term 'Hunter' and 'Half Hunter' and 'Double Hunter' applied to watches that, by my understanding, are not Hunter cased at all. Here's how I understand it:

Hunter = a watch with a hinged cover over the dial, operated by a spring, and closed with a latch that operates by pushing on the crown, or a button atop the pendant. Generally these have a double hinged cover on the back.

Half Hunter = a watch with a hinged cover over the dial like the Hunter, but with an opening that allows you to see the hands.

Open faced watches with single or double hinged backs are just that - open faced. Not hunters.

Am I wrong here?

 

Two types exist

'Lepine' = Open faced with crown at '12' and sub seconds at '6'

'Hunter' = Crown at '3' and sub seconds at '6'

These describe the movement and are and standard Horological terms. Even wristwatch movements can be termed hunter or Lepine style. It has NOTHING to do with the case!

Full hunter' describes a case with cover on front and back
Half Hunter' describes a similar style BUT an opening to read the time without popping open the 'hunter' top.

Then we have other variations (names) that describe how the 'hunter' is opened like 'savonette'

Regards
a

 

To address the OP - single hinged backs are pretty common. Elgin used them on a number of their Streamline model cases back in the 1920s. They're a little less dust-resistant than a double hinged back, but allow you to make the watch thinner. The thing is, in a double hinged back, the two covers are each thinner than you can make the back on a single hinged case.

Single hinged backs aren't particularly fragile. Very, very few wrist watches have an inner dust cover, yet we don't see them as being terribly fragile.