Great advice from all above, if I may add make the investment and purchase the K98K book listed on the top of this page. Knowledge is power and can save you big money and make you money on your purchase. Another bit of advice is to get out to your local gun shows, not necessarily to buy a k98 but to get as many examples in your hands as possible to physically examine. Once you know the basics of what to look for after handling 15 to 20 rifles you will be amazed on how quickly you will be able to spot a turd rifle or a potential gem. Also study the pictures of known correct examples listed on this site. Good luck and enjoy the hunt!
This is true, and I'll be the first to point people who want to learn more about these guns to these books, but there's a pretty big caveat here:
Books aren't cheap. Volume 2 of the K98k books costs about ~$150 after shipping (in the US), and if you want to get the other two volumes you're looking at the secondary market which tends to be more expensive. It's not an exaggeration to say you could easily end up dropping $500 on the full set. That's roughly on the lower end of the cost of an RC. Glancing at my shelves I'm sure I've got over $1000 sunk into books on Mauser rifles alone, and that's ignoring things like the G/K43 books or the M1 Carbine books or any of the other random stuff I've accumulated over the years.
I recommend that people get an honest, inexpensive, beginner rifle before they dive deep into the books. If nothing else it gives you something to take apart and have in front of you while you're reading, and they make excellent study pieces.
Plus, the books are references, but they won't make you immune to getting taken by a ground and renumbered SN. There is a lot that goes into developing that skill, and even advanced collectors can have disagreements about it. Well, sometimes, some fakes are just really obvious. I've been squinting at German serial numbers for almost two decades now and frankly I feel like I only just have the beginnings of a grasp on spotting the more careful hump jobs. The way to build up that skill isn't necessarily to have the books, it's to look at hundreds, thousands of pictures of parts - both good and bad - and get a feel for what they look like.
All of that is knowledge that takes a very long time to develop, which, again, is why I always encourage people who are just getting into these guns to start with an honest, less collectable gun that they can have fun with and enjoy while they spend the time to teach themselves what they'll need to know to get into the more advanced items.
edit: and don't take this as me saying people shouldn't buy the books. They should, they're great, I own them and use them a lot. But to me at least it seems better to tell a new collector to buy a $500-800 rifle that you don't need a ton of experience to intelligently purchase rather than $500+ in books in order to dive into the deep end on $1500+ rifles where their inexperience might still end up with them buying a turd.
