Kylelew

I bought a new fully rifled slug barell and scope for my Mossberg 835 ulti-mag. This gun has only been used for turkey hunting since I'm just getting back into to shotgun hunting for deer (I bowhunt a lot). Well i take it out today with a buddy and was going to sight it in. the guy at the shop put a new Bushnell Banner Dusk and Dawn 3x9x40 scope on it. While he was at it he went ahead and bore sighted it. My buddy shoots the first shot with it today at 25 yards, and its on the paper just about 4 in. low and 5 in. to the right. We make an adjustment with the scope and I shoot the next shot and it hits the same hole! We mess around with it and finally get it to shoot descent at 25 yards, so we take the target back to 50 yards. First shot, way low and way right, mess with it some more and get the height right, and make one last adjustemtn cause we only had 1 slug left, and what do ya know the last shot wasn't even on the paper!!! this thing is killing me, we shot 2-3/4" Lightfield slugs out of it. What do you guys think is going on?? Need a different ammo?? HELP!!!