Stud driver and spring therefor

A stud driver comprising:

• a housing;
• a piston arranged for reciprocating movement in said housing, said piston being rapidly moved in a driving action by a propellant for driving a fastener into place, and said stud driver further comprising:
• a spring of an elastic deformable material comprising a substantially cylindrical, axially elongated sleeve of an elastomeric material for returning the piston to a piston starting position after a driving action;
• and
• a piston rod of reduced diameter extending from said piston, wherein said piston rod is surrounded over at least part of its length by said sleeve of said spring, wherein said sleeve has an end proximate said piston and an opposite end further away from said piston;
• and
• a resilient braking structure axially disposed with respect to said sleeve outside of the opposite end of said sleeve and having an opening through which the piston rod moves, said sleeve of said spring changing length in an axial direction of the piston rod upon a driving action, and said spring providing a return movement for the piston upon completion of the driving action;
• and
• wherein the resilient braking structure comprises a moveable end wall through which the piston rod extends and a ring-shaped body of elastomeric material on an opposite side of said moveable end wall from said sleeve, said end wall having a central opening that reduces in diameter along said piston rod for cushioning an impact of the piston during a driving action.