Are you running the stock sights? Barrel length might help too, but not if the problem is getting a consistent sight picture. The stock sights are "combat" sights which are designed for quick target acquisition, not precise shot to shot groups like a target sight.
I have an RMR red dot on mine - helps with my older eyes. I can hit a 8 inch plate 10/10 times at 50 yards, and 7/10 at 75 yards. Thats with a stock barrel. A good shooter like Hickock45, can hit more consistently even out past 100 yards. I'm not there yet, but I'm improving.