Ruger SR-762 Picatinny Rail

[Morrey]

New gun, looking at options. Gun comes with 2 3" picatinny rails that attach to the forearm at 3, 6 and 9 oclock. These sections are drilled so the holes line up with the holes in the forearm.

Is this a proprietary system in that Ruger only fits these rail sections, or is it universal in that I can buy off the shelf rail sections that have holes to line up so they fit?

Thanks!