Whether a club is a “blade” or a “cavity back” has nothing to do with how far the shot goes. Those are terms to loosely describe the appearance or the category of club. As far as the clubhead goes on an iron, the factors that determine how far a shot will travel are the mass and dimensional characteristics (cg location, MOI) and loft. Of course the length of the overall club, the total weight of the club, the club head speed the player generates, the attack angle, the ball, all are factors in how far an iron shot travels. Comparing apples to apples between a blade or cavity back, assuming same loft, weight, shaft flex, club length, ball type etc. and assuming shot in the center of the face, there would be no difference in distance between the two types of clubs. Hit off center, IF the cavity back has more perimeter weighting and is more stable, then it could provide slightly more distance on off center hits. Understand, just because a club is a cavity back does NOT mean it will always have more perimeter weighting or be more forgiving than a blade. You would think so, but it doesn’t. The stability of the design, it’s forgiveness, is based on it’s overall mass and dimensional characteristics, not it’s appearance as a cavity back design or a blade design.