Bullet hitting sideways

[Reconshane]

I have two mausers. One, a 1915 GEW 98 that shoots extremely accurate is barreled for the Spitzer round (s stamp on the barrel and 42 stamped on the lange visor sight). The other is a 1916 GEW 98 Karabiner without the Spitzer markings. I have fired two different surplus ammo types and the Hornady ammo through both rifles but everything shot from the Karabiner comes out spinning like a saw blade. Anyone have any insight on this?

[donp326]

For some reason the Karabiner cannot stabilize the bullet.  Copper fouling in the rifling or the rifle barrel is shot out, meaning the lans are too worn the stabilize the bullet.