Sig 522 picatinny rail spec - need a measurement

[Red_5]

Recently got myself a Sig 522 classic and like it quite a bit.

I have however run into what *could* be a minor annoyance regarding the picatinny rail on the receiver. Upon the (attempted) mounting an optic borrowed off my "Recce-Style" black rifle I discovered the rail is narrower than a mil-spec picatinny by about .015

The mount is a quality piece, GG&G "Accucam" scout rail with the optic mounted to it with Burris XTR rings. When mounted on the Sig, it was loose on the rail with the cam locked down so I took a digital caliper to the rail.

Mil-Spec is .835 (which is what my BCM, CMMG and Sabre uppers measure)
My 522's rail measures .820...

An interesting bit is that the Sig rear sight that came with the rifle fits the rail pretty well and can be secured with a reasonable amount of torque on the mounting screws. This leads me to believe that the rail is dimensioned to Sig-spec and not mil-spec.

Anyone else with a 522 run into this or care to take a measurement and post the results?

[Red_5]

It would seem that the 522 top rail is not mil-spec. I expected this would be the case, and it's not a big deal, just an observation.

It's worth noting though that any sights or optics mounted to the rail with a mil-spec mount/rings will be offset by half the dimension that the rail is undersize (.015).

Also, the Sig peep sight that ships with the 522 will not fit a mil-spec rail, it's too tight. Not like anyone would want to use it on anything else... :-p