Is that scope mounted in asee through type mount? If that's the case I would think it's just the relatively steep angle of the barrel compared to the scope's sightplane. To be 2 inches high at 25 with say 3 inches difference bore to scope centerline is 5 inches of 'rise'...I'd say those bullets are still going up. Try to zero the gun at 50 and check where they are at at 25. If it's not that simple then you could be looking at a parallax issue, had a scope once that as long you shot at 100 yards everything was great...25 I'd miss the broad side of a barn!