Bushmaster Carbon 15 Optics Ready

I purchased a Bushmaster Carbon 15 Optics Ready, it came with a flat top P rail, two risers, and a Bushnell Trophy 1X28 red dot sight. Mounted the sight and went to range, shots were all over the place. Just to make sure it was sight and not shooter, picked up my plinker Hi-point 995 9mm with cheap BSA red dote and put several in a 4" circle at about 125 yards. I will be the first to admit that I know next to nothing about optics or mounting scopes. Was looking at Leapers 5th Gen 4x32 mini CQB and 5th Gen 6x32 mini rubber covered. I plan on having them professionaly mounted and bore sighted. Is there something else out there I need to look at under $100. I need something good up to 200yds. Thanks in advance for any help.

Hi Duke. You might want to post this with out gun guys under riflescopes or laser red dot scopes. Telescopes, here, refers to astronomy.