Disclosed herein is a method of making a spring core (12) for a bedding or seating product (10). The spring core (12) has coil springs (26) having unknotted end turns (72, 74) made from high tensile strength wire. In each embodiment, the end turns (72, 74) of the coil springs (26) are generally U-shaped having one arcuate leg (76) longer than the other (78), the legs (76, 78) being joined by a connector (80) having an arcuate bump (81) therein. The springs (26) are oriented in the spring core (12) such that a long leg (76) of one end turn (72) abuts a short leg (78) of the adjacent end turn (72) prior to being wrapped in helical lacing wire (32). The high tensile wire enables the coil springs (26) to be manufactured using less wire than heretofore possible.