From the rulebook.
"Any load with a velocity greater than 1290 FPS (Feet Per Second) with
maximum shot charge of 1 1/8 ounces, or 1325 FPS with a maximum shot charge of 1 ounce, or 1350 FPS with a maximum shot charge of 7/8 ounces or less, as measured in any individual shotshell. These velocities are maximum and no individual shotshell shall exceed these limits for the designated shot charge. In addition, no load containing more than 1 1/8 ounces or any shot larger than Number 7 1/2 can be used. Shot charges are maximum and no charge may exceed the charge amount by more than 3%. Steel shot in Number 7 will be acceptable as long as velocity criteria are the same as for lead shot shells."
So I would say that you don't have anything to worry about shooting 1250fps shoot the ones you have.
Bob Lawless