Steve, The Kar98a should be a small ring large thread receiver (1.1 dia thread). The Gew 88 barrel has the small thread. (.980 dia.) So it really won't work. (I don't now if you could machine the tenon off and start over with threading??) Going The other way --from large threads to small threads is doable. I rethreaded a 7mm k98 barrel to Gew 88 dimensions for a Gew 88 action that I think I got from You!! It worked great. Also with the Gew 88 barrel is the small bore (.318 I believe) You don't want to contend with that. My 8mm reamer pilot wouldn't even fit in the bore. Best to look around for a 98 barrel. Salt Flat