call them; I'm sure a lot of guys use their loads in shotguns designed black powder.
However, the Batavia Leader I believe was proofed for nitro shells; even twist barrels. I would not shoot modern off the shelf loads.
Have the gun inspected by a competent gunsmith for pits; and measure wall thickness on the barrels. Never know what was done to guns that have been around 100 yrs.
I have an old Batavia Leader ser.# 100xxx made in about 1908; twist barrels with multiple small dents and considerable pitting. About 1970, some 3 3/4 dram eq. loads were ignorantly fired in it and it stayed together. I have since used Four Tenner inserts in the gun. Can't get them anymore except some come up on the sites sometimes. I have thought of using 12 to 20 ga Gauge Mates chamber inserts. That would give added strength to the chamber and a rapid pressure drop in the barrel.