Schweeeeeet.
IMHO they must be better than a Mauser, because the benchresters use them.
However, I suppose "better" depends on what you want to use it for. You can probably get smaller groups with a properly-built rifle on a Nesika action. That won't necessarily make any difference to you if you are using it for hunting deer, and since it would probably weigh more than that Mauser, you might consider the Nesika worse.
You might give Russ Haydon a call; he sells Nesika actions, among others. He might know about the stock, too. I don't recommend emailing him, since he only checks it about once a week. See:
[url]http://www.shooters-supply.com/[/url]
BTW, if you happen to make it over to Washington for the Puyallup WAC gunshows, he is usually there on Saturdays. Great guy to talk with, and he has good prices too.