This is not an Omega BOR, is it?
The Omega ones have solid ends to the links and are much easier to adjust. In there is a spring bar (similar to the ones at the watch head) and you compress both sides of that bar to remove the links, just like removing a strap from the head. Here's one below and you can see the holes where the spring bars are.
View attachment 730926
Cheers, Chris
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