The Triple Seven and Pyrodex pellets are supposed to be equal, but when I tested one against the other, there was a different POI between them. It was not much, but as I remember the Triple Seven hits were a little higher and to the right in the same rifle, with the same load.

It will be close, but I would recommend a range session to double check. Also watcht the breech for a hard crud build up when shoot Triple Seven. Nothing swabbing will not cure though.