How far would you go?

A few months ago, I walked into a pawn shop to rack check for good rifle deals as I often do. I immediately fell in love with, and bought, a 1915 Mauser Gewehr 98 for $200 from him. I knew it would be a project, but I couldn't get it out of my mind. It had been sporterized to 6mm Rem a few decades ago, apparently in Europe according to an old gunsmith I know, and even though the stock needs a lot of love, the action and heavier-than-average barrel are in phenomenal condition. After having it checked over for condition and cast for caliber/cartridge (since the barrel wasn't stamped), I decided to take it for a spin with a box of Hornady 6mm Rem I picked up. In the end, to leave an even longer story shorter, I split 2 of the 4 cartridges I fired through it (yes, factory loaded new). Clearly, I have a serious issue of too much head space. I have pondered for the last several weeks how much work and $ should be put into this rifle and what path to take with it. Although I'm sure that this rifle has a very checkered past, I have this gut feeling that it would be a damn fine shooter with just a little TLC. Bottom line, I guess my question is, how much does it cost to have a barrel dropped back to reduce head space (doesn't need to be a full turn since it's not tapped for sights) and, is it worth it? I'm able to do the stock work myself but I've never had lathe work done by a gunsmith so the cost of fixing the headspace scares me. Any guidance would be greatly appreciated.

Kp321, I did not receive a PM from you.

As for the rest, I posted a picture of the four fired rounds on here. The gunsmith I took the rifle to did do a chamber cast (though he did it with sulfar not cerrosafe) and we matched it side by side with a 6mm Rem Round and they looked the same. According to him, the barrel is definitely a 6mm and since it was built on an original Mauser action, it has to be a x57mm cartridge...meaning a 6x57mm, otherwise known as a .244 Remington/6mm Remington." I am not a smith, but the chamber cast and 6mm Rem cartridge did appear identical to me. What did make him curious is where and how the cartridges split. I asked him about the headspace and he said, "there is a little excess headspace, but that's not out of the ordinary for a sporterized Mauser and there shouldn't be enough to cause that kind of split".

Maybe I just need to take it to another smith for a "second opinion" of sorts or just do a cerrosafe cast myself. Thoughts?

Besides having it recast for caliber again, does anyone have any thoughts on the brass pic I posted if the rifle is in fact 6mm Remington?

The fired brass was brand new factory Hornady 95 gr SST 6mm Remington. That's not to say the rifle is definitely a 6mm Rem if the previous gunsmith wasn't correct. I'm set up to have the rifle looked at again by a competent gunsmith.