Hey guys, need your help/advice. I have the above 12gau shotgun and went for deer this week for the first time. Now last month I went up north for some grouse to break her in and fired a box of target load threw her. Had no problem hitting a few birds during that weekend (using Federal ammo). However my buddy who is fully licensed purchased the ammo (as my Firearms license is still in the process) and purchased Winchester slugs 2 3/4 1oz, Supreme I believe, the problem is the ammo I was using costed me my first 2 does (40yd shoots) sitting position as I found out later it shoots 2ft high and to the left at 50 yards using a make shift bullseye out of cardboard and this was validated by 2 different hunters I was up there with and they were shooting from the kneeling position. I was using improved mod. choke, is this possibly certain ammos react differently. I was told Rottweiler is the ammo I should be using for this shotgun, could it be anything else???....any info./advice will be appreciated