P.S. for Aurelius.
As you say you a beginner with Mausers, I think you deserve a little more explanation.
The know how in the books helps you to
1) Recognize that the "Original mint K98" you are being offered is, in fact, a mixmaster of restamped Yugo
bits.
2) Recognize that the beat-up 1893 offered at a wallhanger price was in fact a rather rare Boer Mauser.
3) Reject the ones that look externally OK, but are in fact useless, or even dangerous, for shooting.
You did not say WHICH type of Mauser you purchased. I am cautious, even suspicious when you mention cosmoline, as this does not sound original. And sometimes sellers will smother the rifle in grease a) to make it look as if it came out of an arsenal b) to hide nasty stuff under the waterline. In any case, the gunge must be completely removed if you want to actually use the rifle, as the heat of firing will melt the grease so that it soaks right through the wood, ruining both finish and (eventually) the wood.
And finally, a check by Mauser experts is probably more reliable than a check by the typical gunsmith who has no specific knowledge of old service rifles. He will just pop in SAAMI headspaces gauges and tell you your rifle is unsafe, thus saving his butt, to use an expression common on your side of the pond. If you find a gunsmith who regularly handles 98-action hunting rifles, that would, of course, be different. So if there is something like a Mauser club in your area, get in touch!
Patrick