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It works good. Probably the best solution for mounting optics short of permanently pinning the barrel to the receiver and tapping the receiver. It is convenient. As the barrel and optic can be removed and reattached without affecting your point of impact.
I have a cantilever barrel with interchangeable chokes on my Remington 870 and use a 1.75 to 4 Bushnell Trophy shot gun scope. I use it for everything and I love it.