differences between Weaver and Picatinny rails?

[Cheeseybacon]

So what's the difference between Picatinny and Weaver rails? Is one preferable over the other or have an advantage of the other? Are both of these rails fairly common standards or is one typically utilized more often than the other?

I checked out Wikipedia and it wasn't much help other than saying that the slots on Weaver rails are spaced 3.8mm apart while Picatinny slots are spaced 5mm apart.

 

[Slamfire]

Did you happen to see a standard called out for the Weaver mount? No. Did you happen to see a standard with dimensions called out for the Picatinny?, Yes. http://en.wikipedia.org/wiki/Picatinny_rail

Well there is the difference. If you are going to make mounts, and make devices to fit the mount, to what dimensions are you going to cut a Weaver mount to? Weaver dimensions are proprietary. And if your customer complains about his off brand Weaver rings not fitting your Weaver mounts, you have a problem because those Weaver mounts were made to someone else's best guess of Weaver dimensions which is different from your best guess.

That is why the Picatinny rail and dimensions are being used by a lot of manufacturers: there is a “open source” standard. Everyone can read that standard and make parts that will fit. Proprietary standards are a pain, and if you don't believe me just randomly buy an earphone jack and stick it into your cell phone. Odds are it won't fit; cell phone makers want you to buy their earphones. I like “open source” standards, but Corporations like proprietary.

There is nothing intrinsically better between the mounts other than buying picatinny dimensioned mounts and devices means that things have a high degree of interchangeability.