When there is that much of a drastic change in a short yardage change, it is the scope. I've had the same thing happen while I was sighting in my SKS. I had a bad scope mount and every time I shot it, it was coming loose and the same thing happened. Couldn't even find it on the paper, 2 seconds after grouping it.All you will do is drive yourself nuts and blow lots of ammo.If you get those Sabot slugs, you will be able to shoot hogs at 75 yds.Once you get it to stay on the paper of course. I personally use Rottweil Brennekke slugs out of my Ithaca Model 37 pump and it shoots slugs inside of slugs at 50 yds.