Figuring out weaver and picatinny

[JDP12]

Hey all- insanely stupid question here please bear with me.

How the fork do weaver and picatinny rails work? How do things mount on them? At first I just thought they slid on the end... but then I see it has something to do with the slots in it..What purpose do they serve.. how the fork do you mount stuff on them?

I just don't freaking get it.. If someone could please help me out I would greatly appreciate it.

[dewey-1]

Here is a start.

http://en.wikipedia.org/wiki/Picatinny_rail

You see here also;

http://www.spudfiles.com/forums/picatin ... 18349.html

[jackssmirkingrevenge]

Usually stuff clamps on to weaver/picatinny rails in the same way they do to ordinary dovetail grooves found on most rifles. The slots are there primarily for heat dissipation but occasionally they serve to prevent forward/rear motion by engaging parts on the mounted item, it depends what you're attaching to them.

[Daltonultra]

The slots actually have nothing to do with heat, other than allowing the rail to expand and contract without warping.
Their main purpose is to provide retention for mounted items. Many accessories that clamp onto the rails have to be very securely mounted(i.e. scopes, lasers), so they have either a retaining button, or a bolt through their clamp that sits in those slots, positively locating them.
Otherwise, you get a situation like my Dad's break-barrel pellet gun. It uses a dovetail mount, very like a rail, but narrower, and without the slots. The scope that is clamped to it has a bad tendency to "walk" off the end of the dovetail after twenty or thirty shots.