It's an M96
Well, assuming you have something that's not a prototype or been altered by someone else, that LONG rifle is a Swedish M96. They're very fine rifles, indeed.
The M96 used to be a favorite for sporter building, because the actions are some of the slickest Mausers ever made. The Swedes never used corrosive primed ammo, so your bore may be in prett good shape as is. The M96 is overshadowed a bit by the M98 because the M98 was built with more safety features to protect the shooter if you do something stupid. The action is plenty strong - but American ammo companies 'dumb down' the loads. The Euro manufacturers like Wolf, PRVI, Norma and others load it somewhat hotter.
The 6.5 Swede is legendary for accuracy, and is still popular in Sweden for both matches and moose hunting (yes, moose). The 139 grain load is the most frequently seen.
A rifle made in 1900 or so (like mine) is a quality, well-made, reliable firearm.
Most guys will tell you that on a used firearm you should have a competent gunsmith check it first, but many of us, too, wouldn't bother to since the Swede wasn't made under wartime duress by slave labor. YOU must make that determination.
The Swede isn't as common as they used to be - they were never manufactured in huge numbers like the M98, so there weren't a zillion of them on the market in the first place, and since they've been favorites for customizing, are getting rather scarce. The point here is carefully consider if you want to alter it - go ahead if that's what you really want, but know that
it's a rifle that's appreciating in value due to diminishing numbers.
Go here
http://www.surplusrifleforum.com/ to get more general info on your rifle. They're a bunch of good boys like the members here
and are very good at answering more questions.
Good luck.
