Originally Posted by
Bass Ackward
I'm going to take another twist. Ain't always you.
What makes me consider this is the fact that we are taking about a single gun. A single gun with what kind of rifling?
We have had numerous posts where guys have a great load at a certain distance only not to hit paper when the distance is increased. With cast or with jacketed.
Don't clean your barrel well and what you describe is guaranteed after awhile. Makes like a smooth bore. Some rifling types are more prone than others, like polygonal types.
So hand your pistol to someone else and see if the pattern holds. If it is bad for him too, then maybe you have to look farther. If it ain't the gun / load, then the other guys covered that.