Iron-type golf clubs and golf club heads

An iron-type golf club head comprising:

• a top surface, a sole, a heel, and a toe;
• a ball striking surface having a ball striking area;
• a rear surface opposite the ball striking surface, the rear surface having a muscle portion extending from the heel to the toe;
• and
• an interface surface adjacent an upper edge of the muscle portion, wherein the interface surface includes a convergence point located closer to the toe than the heel, and further includes a first interface surface extending from the heel to the convergence point and a second interface surface extending from the convergence point to the toe, wherein the first interface surface and the second interface surface form an interface angle at the convergence point, wherein the interface angle is an obtuse angle, wherein the interface angle is between approximately 115 degrees and 155 degrees.

An iron golf club comprising:

• a blade-type golf club head comprising a body forged of a metal material, the body having a hosel, a top surface, a sole, a heel, and a toe, the blade-type golf club head further comprising a ball striking surface, and the club head further comprising a rear surface opposite the ball striking surface, the rear surface having an upper blade portion and a lower muscle portion with the upper blade portion separated from the lower muscle portion by a blade interface, wherein the blade interface includes a first blade interface and a second blade interface intersecting the first blade interface at a convergence point located closer to the toe than the heel, wherein the second blade interface extends upward at an interface angle from the convergence point and between the first blade interface and the second blade interface, wherein the first blade interface extends parallel to the sole, and wherein the upper blade portion and lower muscle portion extend across the rear surface from the heel to the toe and further with the upper blade portion extending from the top surface to the blade interface and with the lower muscle portion extending from the blade interface to the sole,
• wherein the upper blade portion has a generally uniform thickness from the heel to the toe, and
• the lower muscle portion has a thickness greater than an upper blade portion thickness, and
• a shaft that attaches to the club head at the hosel.