C96 pistols don't have a barrel, per se. The entire upper receiver is a single contiguous unit. The best way to "rebarrel" a C96 is to cut off the original barrel and then bore out and thread the receiver so a new barrel can be installed. Otherwise your only real option is to seek a new upper receiver for the gun.
Not so. There is a service available for C96/ M1930 relining to 7.63x25 by a registered machinist and gunsmith with 30 years experience - with all work done in Canada. You end-up with as-new chamber and bore (.308" diameter 6 grooves). The liner features hammer forged rifling. Re-barreling is also available - to either 7.63x25 or 9mm. Prohib (12.2) broomhandles (Bolos and 1920 conversions) can be re-barrelled to restricted only. PM me for details.