Hi Kim. No, you do not need a Monte Carlo. If you find a BT-99 you like, don't be concerned about whether it has a straight, or a MC stock. Both may not fit you the same, but both will work essentially the same, since as Joe said, all BT-99's are pure trap guns. The purpose of a MC on a trap gun is, it keeps your eye up level with the rib on the barrel, while dropping the recoil pad down a little, to meet your shoulder properly. What this does is, helps you keep your head properly upright while allowing full recoil-pad contact on the shoulder. There's a device that stock-fitters install called a Jones Adjuster, which does much the same, plus it allows you to twist the recoil pad around to fit your shoulder muscles' "pocket." We've had adjustable combs installed on both conventional & MC stocks, and both work the same. The stock fitter cuts the top part of the comb's wood out, then reinstalls it on posts, so the comb top can be moved up-down-left-right, to better fit your face profile. You'd only have this done if needed to get your shooting eye lined up perfectly with the rib, or to raise or lower the eye. You may pick up a gun that fits you well & doesn't need this, or not. I'd recommend Rollin Oswald's book (above) for in-depth info on gun fitting. Phil E