I looking get an UTG 3-9x32 Bugbuster Scope for my M&P 15 sport & in the pictures online the scope looks pretty tight to the rail. Reviews I've read, many mention risers. I'm not looking to co-witness. But, I need to clear the mbus rear sight. Are the 0,5 inch risers enough to clear the mbus or should I go with the 0.83 risers? I do not want to raise the scope to high & then need to add a cheek riser. Thanks, DK