The current M77 in 7mm Mag uses a 1 in 9.5 twist. Savage and Browning use 1 in 9.5 too. Remington uses 1 in 9.25.
To find out if your's is different, not likely, put a solvent soaked(for lubing) patch on your cleaning rod and stick it into the chamber. Mark the rod at the chamber and near the handle on top of the rod. Push the patch through the barrel until the handle end mark makes one complete turn. Mark near the chamber again. Measure the distance between the chamber marks. That'll give you one turn in whatever distance is between the marks.