A 12" rise at 100 after zero at 25 yds is a ballistic impossibility with anything that resembles a normal gun /scope installation. A 30 caliber bullet zeroed at 25 will be climbing at 50 and then drop back to zero at 100 or close to it. I can't see how a scope mounted high could give a 12" rise. One thing I would check is the scope mounted parallel with the barrel. Different sized mounts from front to back resulting in a low front objective might give a weird bullet path...just thinking out loud.