I finally found time to duck into the gun room and check my copy of Forker's Ammo and Ballistics II. The heaviest factory load shown is Remington ammo with a 60-grain Partition. If that load will shoot in your rifle, it might work. However, Midway doesn't show that load in their catalog this year, so it may be discontinued. You might be able to find a box or two if you look around.
Midway does show the 60-grain Partition being offered in Federal's Vita-Shok line, so that's another possibility. Lastly, Double Tap loads a 55-grain TTSX that would probably work just as well as the Partition. They are listed in the Midway catalog, as well,
I would try a box of each and see what shoot best in your rifle.
