If it's a .30, odds are the bolt is cracked due to attempting to shoot hot Soviet 7.63 rounds through it.....
That is an old myth that has been floating around for so many years that a lot of people believe it. The exact opposite was true during WW2. The Soviets loaded their 7.62X25 ammo to just under 1400 FPS out of a Tokarev's barrel. The 7.63 Mauser was loaded by the Germans to 1575 FPS out of a C-96 Barrel. Source for this is "Small Arms of the World," by Smith and Smith.
My broomhandle has digested thousands of rounds of rounds of mixed surplus and commercial 7.62X25 ammo in the last 20 years
My Luger came with a 9mm barrel mounted and the original 30 Mauser barrel (serial number matched, excellent condition) as part of the package. I have always shot 9mm. The guy I bought it from said he just bought a used 9mm barrel, unscrewed the .30 Mauser barrel and screwed in the 9mm barrel. It asked him about head spacing... he replied "not a problem". And it has never been a problem. My point... don't rule out a 30 Mauser Luger. Or just pick up one of these:
http://www.gunsandammo.com/handguns/a-luger-in-45-acp/
I bought my Luger at a gun show from a P38 collector. I bought my P38 at a different gun show from a Luger collector. I feel I got better than average deals on each.
I think perhaps you mean .30 Luger? Lugers were never made in .30 (7.63) Mauser. The cartridge is too long to fit in magwell.