These are for the most part a terrific mount for DGR's. They allow for quick exchange between scope and iron sights with a twist of usually 2 levers.
The drawback that most people site is that the primary portion of the mount is usually screwed to the left side of the receiver for right handed users. If you decided to change mounting methods, something would have to be done with the screw holes.
Other than that the ability to return to zero is exceptional with the use of a stop screw and detents for the mounting screws.
We have given up on the screws into the side of the receiver and make the receiver with the primary mount integral with the receiver. It makes the receiver a little more expensive to make but it is truly a neat solution to scope/open sight shooting.
Bill
I love those old G&H mounts, but they belong on a rifle such as a Westley Richards, H&H or of that ilk...They leave a clear reciever and I dearly love that with iron sights.
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Ray Atkinson