It is actually a LH Montana 458 action. I want to put an RMR on it, but don't know the proper mount. Thanks.

Check the Trijicon website for RMR mounts. They make a bunch for all kind of bases. Just decide what set-up you want, buy the proper RMR mount and get the appropriate base made by whomever you prefer.

Put a Weaver or Picatinny base on it, and mount the RMR to that.

George

Thanks!

And let us know how it works--