Back years ago scopes didn't have internal adjustments. You simply mounted a scope and adjusted the rings for windage and elevation. Rifles didn't come drilled and tapped from the factory until the 1950's and 60's. To mount a scope your gunsmith had to drill and tap the holes. It was common for them to not be perfectly aligned with the barrel. Windage adjustable mounts were the answer to the problem. They corrected poor gunsmithing.
Today, with rifles coming from the factory with pre drilled mounting holes it would be extremely rare to find a rifle that needed windage adjustable mounts. If I had rifle that needed them, I'd return the rifle as defective before using them on a modern rifle. They might be necessary on an older rifle.
Compared to more modern mounts with a cross slot, or with the bottom half of the ring made into the base they are simply not as strong and dependable for precision shooting. You simply won't see anyone interested in accuracy use them.
They are expensive, heavy, complicated, hard to mount correctly, and if mounted incorrectly will damage the scope. After mounting it is fairly common for the windage screws to shoot loose resulting poor accuracy. The front dovetails will wear giving a loose fit between the ring and base over time.
Despite they all steel construcion they are not particularly strong. The front ring is held in place by a steel rod about 1/8" in diameter that fits into a dovetail in the base. The rear ring is held by 2, fingernail sized slivers of metal on each side.
Lots of guys still use them simply because that is what they saw grandpa use. But there are far better options today. Unless you actually have a rifle that needs them because the scope mounting holes are drilled incorrectly.
