Paul,
You stated that the crack was 4" below the chokes. Is that from the start of the choke constriction or from the muzzle? Either way the crack is between 4" and 8" from the muzzle. Your gun has first generation muzzle porting!
All kidding aside, please do not cut the barrels. The pressure in a barrel is low by the time the ejecta reaches that point. If the barrel walls ajoining the crack have at least .020" thickness then the crack should be able to be repaired to make the gun shootable.
Long ago I read something from Elmer Keith that for a crack or hole near the muzzle he soldered (silver soldered?) a piece of beer can (or other thin stock) to contain the pressure and continued to shoot the gun.
Send your barrels to someone like Brad B. who knows how to weld a crack in Damascus or twist barrels.
Mark
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