Hello, Does the 151k come with sling swivels from the factory? I mean are they even drilled for the sling swivels? I've seen a few pictures of them and they don't even look like the stocks are drilled for swivels. Is this something you do yourself? I know the swivels are the same for the 151M, Ma, Mb & Mc models and probably a bunch of other ones as well. Just wondering. Thanks. Mark T.