Help identifying vintage military spotting scope

This was found amongst my late grandfather's belongings. He was in the Korean war but was also a collector of hunting and military stuff.

There are no markings anywhere on the body and the serial number 10543489 can be seen on the side of a detachable mount adapter.

Any help in identifying the origin of this scope would be much appreciated!

I've attached two pictures of the scope, which measures ~14.5" in length, 2.5" viewing diameter, 2" rear lens diameter.

Thanks in advance!
Katie

That looks like a weapon sight, like tank or perhaps artillery. The dovetail slides into a corresponding mount...rubber eyepiece cushions you from recoil.

Have you removed the detachable mount adapter to check for markings?

M120 Telescope for a 20mm cannon.
M120 Telescope, Straight, for 20mm Cannon, USGI, *Very Good +*

Searching the number you identified plus “telescope” led me there. The US military at least always called scopes like this “telescopes.”

So, it IS what I said... A passage stolen from the book.

Thankyou very much for your help!