Who makes the Luger rifles (based on the M98) that are offered by Kettner? Thanks in advance.

Luger rifles are produced by Zastava

http://www.zastava-arms.co.yu/english/civilni.htm

The "Lugers" are pretty rough although certainly a very reasonably priced sorta MK X type Mauser system.

I purchased one of their Left Hand models as donor action for rifle projects and it has been turned into a very nice 9.3x62.

Rough and requiring much polishing the major complaint is the poor stock and even worse inletting.