Sounds like a .45 Colt and the 2400 is only a moderate load, but one listed for Ruger Blackhawks, I think. In a .44mag, it's a heavy .44 SPL load.

5" to 6" at 100yards is VERY good accuracy (my opinion) from an accurate revolver with open sights.

With the scope, I'm sure you can do better - either with a more accurate load, or with more practise - keep at 'er, you're headed in the right direction.

Way to go! Nice looking combination, the heavy full length rib and all stainless.