Open it up to IC which usually works fine with steel and it will be just as safe as a current barrel of the same constriction....Only thing I would be sure of is that whomever did the work, based the constriction on the step down from the barrel inside diameter. Some of the older guns had smaller insider diameters than todays offerings.
However, perhaps it would be wise to use regular steel velocity loads and not some of the super fast ones that are currently available. Nor would I say for one to use it with a SxS or O/U. Single barrels only....
It is often said that Remington states any barrel they made after 1950, that is fixed modified or less can be shot with steel no larger than 2's. However, I've never tried to verify that with Remington.
Great advice from battue. I’d consider sending to Briley to have it opened up. They'll do you a great job. Briley can also thread the barrel for thin wall chokes, that are rated for steel. Opening the choke a bit would be easer.
