The company itself has been out of business for more than a half-century; so new replacement barrels are not an option. Aftermarket used barrels are hard to come-by; and good sets are expensive, must be of the same frame and bore size, and will require expensive hand-fitting by a qualified gunsmith. If the gun and barrels are in good shooting shape otherwise, I would suggest leaving the barrels as they are (once cut, it is almost impossible to safely extend the tubes; plus the repair will be very evident, and the process would be cost prohibitive) and going with one of two options: have someone like Briley install modern screw-in choke tubes, or have a qualified gunsmith rechoke the existing barrels with a swage choke. The second method would be the least expensive option; and any choke constriction from Modified to Skeet can be created. And, based on personal experience, short barreled guns make for a really effective gun when unland hunting in tight cover.