There was a friend of mine that had the same problem you're describing shooting R.E.A.L. conicals and even maxi balls. He would hit dead center at 50 yards but at 100yards he was always about 4 inches low. He was concerned about this because a lot of his shots were in the 70 yard range. I suggested to him just for kicks, sight the rifle dead on at 75 yards and then see what it does at 50 & 100 yards respectively. This was only a guess at a quick fix on my part.

He did what I suggested. The results he got were at 50 yards he hit the top of a 3" bull and at 100 yards he was near the bottom of the same bull. He felt he could adjust for an inch in difference. I told him to just aim for the top of the kill zone if it was further then 75 yards. That year he filled his doe tag at near 100 long step shotwith a perfect heart shot. I asked him if he aimed for the top of the kill zone and he admitted he had not, but for some reason that conical hit right where he wanted..

You could try add a little more powder and see if it makes the difference your looking for. You could also try adding a wonderwad. Sometimes the increase in pressure will pick that conical up a little longer. Our you could adjust your sights to match your shooting situation.

Good luck with the rifle. I will be interested to learn what you had to do to make the fix...