Did you work up the load for that specific gun? I 've never liked trying random powder charges. Some guns will show signs of high pressures below the max that data lists.

When I work up a load I start with the minimum listed charge and increase powder charges in small increments. I load 5 rounds of each powder charge and shoot them from a solid rest. I shoot them at 25 yards and use a new target for each powder charge. I'll usually shoot through a chronograph while doing this also.

You'll usually see the groups tighten as you near the "sweet spot" for the bullet and powder being used. Usually the groups start to open up when you pass the load the gun likes. I load 454 Casull and just like other rounds sometimes lighter powder charges are the most accurate and sometimes heavier charges are.

I save all the targets from load development. I've often referred back to them years later. Its kept me from reinventing the wheel when I forgot that I already tried a bullet/powder combination.