Proper Weaver mounts are designed so that a cross-bolt fits into a groove in the rail, to lock the mount/sight in place and act like an arrestor block or pin on a dovetail rail. For some reason the Alecto doesn't have this arrangement. I've been waiting for a definitive answer on the red-dot mounting issue before I decide whether or not to go for one.
Bernard's post is very interesting because the sight I would fit is a Barska panoramic red dot of the same configuration as the JSR ones (and the fee-bay specials). I'd rather file a groove in the plastic than butcher my sight though. A few strokes of a rat-tail should do the job I'd have thought.
There's a similar discussion on airgun-tec at the moment.
“We are too much accustomed to attribute to a single cause that which is the product of several, and the majority of our controversies come from that.” - Marcus Aurelius