CraigC is right. Trying to compensate your aim point isn't an answer. Often times when a handgun is shooting high or low at distances out to 25 yds. or more, it is the shooter not the gun. 25 yds. is a long distance off hand if your not a very accomplished shooter with handguns. I have almost 5 decades of shooting under my belt and couldn't possibly sight my handgun in accurately at 25 yds. much less 50 yds. without a good shooting rest. During hunting season I see a lot of this, and it usually involves the shooter using a soda can or paper plate at 50 yds. with a high powered rifle off hand, and results in them missing every deer that comes along. Sights and optics are on the chopping block far too often, and long before a clear determination has been made from a proper shooting rest.
The only reason I've addressed the sight in method, is you never stated the method you used to sight it in. Earlier on in this post someone asked if you adjusted the rear sight all the way down, and you replied yes, it is adjusted as far as it will go, but you didn't specify all the way down.
I always start from a close range, say 20', and work my way out until I've reached my limit with that weapon, that's likely going to be 40 - 50 yds. with open sights on a handgun for the average person.
Another possible and common issue is how you pull the trigger. When depressing the trigger the firearm is pulled down, and often to the right or left, depending on how you hold it, how much the gun weights, and the trigger weight and travel.